阅读说明：本技术 使用子带降噪技术降噪的系统和方法 (System and method for noise reduction using sub-band noise reduction techniques ) 是由 张承乾 廖风云 齐心 于 2019-09-30 设计创作，主要内容包括：本申请提供了一种降噪系统,所述降噪系统可以包括子带噪声传感器、至少两个子带噪声抑制模块和输出模块。所述子带噪声传感器被配置为检测噪声,并响应于检测到的噪声生成至少两个子带噪声信号。至少两个子带噪声信号中的每一个具有所述噪声的频带的独特子带。所述子带噪声抑制模块中的每一个可以被配置为从子带噪声传感器接收所述子带噪声信号中的一个子带噪声信号,并生成用于抑制接收到的子带噪声信号的子带噪声修正信号。所述输出模块可以被配置为接收子带噪声修正信号,并基于子带噪声修正信号输出用于抑制噪声的噪声修正信号。(A noise reduction system may include a sub-band noise sensor, at least two sub-band noise suppression modules, and an output module. The sub-band noise sensor is configured to detect noise and generate at least two sub-band noise signals in response to the detected noise. Each of the at least two sub-band noise signals has a distinct sub-band of the frequency band of the noise. Each of the sub-band noise suppression modules may be configured to receive one of the sub-band noise signals from a sub-band noise sensor and generate a sub-band noise modification signal for suppressing the received sub-band noise signal. The output module may be configured to receive the sub-band noise modification signal and output a noise modification signal for suppressing noise based on the sub-band noise modification signal.)

1. A noise reduction system comprising:

a sub-band noise sensor configured to detect noise and generate at least two sub-band noise signals in response to the detected noise, each sub-band noise signal having a unique sub-band of a frequency band of the noise;

at least two sub-band noise suppression modules, each of the sub-band noise suppression modules configured to receive one of the sub-band noise signals from a sub-band noise sensor and generate a sub-band noise modification signal for suppressing the received sub-band noise signal; and

an output module configured to receive the sub-band noise modification signal and output a noise modification signal for suppressing the noise based on the sub-band noise modification signal.

2. The system of claim 1, wherein the sub-band noise sensor comprises:

an acoustoelectric transducer configured to detect the noise and convert the noise into an electrical signal; and

a sub-band decomposition module coupled to the acoustoelectric transducer, the sub-band decomposition module configured to decompose the electrical signal into the sub-band noise signal.

3. The system of claim 2, wherein the subband decomposition module comprises at least two band pass filters, each of the band pass filters having a unique frequency response and configured to generate one of the subband noise signals.

4. The system of claim 3, wherein:

a first one of the band pass filters has a first frequency response and is configured to generate a first one of the sub-band noise signals,

a second one of the band pass filters has a second frequency response and is configured to generate a second one of the sub-band noise signals, wherein the second one of the sub-band noise signals is adjacent to the first one of the sub-band noise signals in a frequency domain, and

the first frequency response and the second frequency response intersect at a frequency point that is proximate to at least one of a half-power point of the first frequency response or a half-power point of the second frequency response.

5. The system according to claim 4, wherein the first frequency response of the first band pass filter and the second frequency response of the second band pass filter have the same frequency bandwidth or different frequency bandwidths.

6. The system according to claim 1, wherein said sub-band noise attenuation module is integrated into said sub-band decomposition module.

7. The system of claim 1, wherein the sub-band noise sensor comprises:

at least two acoustoelectric transducers, each of the acoustoelectric transducers having a unique frequency response and configured to generate a sub-band noise electrical signal by processing the noise; and

at least two sampling modules, each of the sampling modules configured to receive one of the sub-band noise electrical signals and sample the received sub-band noise electrical signal to generate one of the sub-band noise signals.

8. The system of claim 7, wherein one of the acoustoelectric transducers comprises:

an acoustic channel component configured to filter the noise to generate sub-band noise; and

a sound sensitive component configured to convert the sub-band noise to a sub-band noise electrical signal.

9. The system of claim 7, wherein one of the acoustoelectric transducers comprises:

a sound sensitive component configured to convert the noise into a sub-band noise electrical signal.

10. The system according to any one of claims 7 to 9, wherein:

a first one of the acousto-electric transducers having a first frequency response and configured to generate a sub-band noise electric signal corresponding to a first one of the sub-band noise signals,

a second one of the acoustoelectric transducers has a second frequency response and is configured to generate a sub-band noise electrical signal corresponding to a second one of the sub-band noise signals, wherein the second one of the sub-band noise signals is adjacent to the first one of the sub-band noise signals in a frequency domain, and

the first frequency response and the second frequency response intersect at a frequency point that is proximate to at least one of a half-power point of the first frequency response or a half-power point of the second frequency response.

11. The system of claim 10, wherein the first frequency response of the first acoustoelectric transducer and the second frequency response of the second acoustoelectric transducer have a same frequency bandwidth or different frequency bandwidths.

12. The system of any one of claims 1 to 11, wherein the sub-band noise sensor generates the sub-band noise signal in a frequency band that overlaps the frequency band of the noise.

13. The system according to any of claims 1 to 12, wherein at least one of the sub-band noise suppression modules comprises:

a phase modulator configured to receive a respective sub-band noise signal and generate a phase modulation signal by modulating a phase of the respective sub-band noise signal; and

an amplitude modulator configured to receive the phase modulation signal from the phase modulator and to generate the subband noise modifying signal by modulating an amplitude of the phase modulation signal to suppress the corresponding subband noise signal.

14. The system of claim 13, wherein the phase modulation of the respective subband noise signal comprises a phase inversion of the respective subband noise signal.

15. The system of claim 14, wherein the phase modulation of the respective subband noise signal further comprises compensation for a phase offset of the subband noise signal in propagation from a subband noise sensor to the phase modulator.

16. The system according to any of claims 1 to 12, wherein at least one of the sub-band noise suppression modules comprises:

an amplitude modulator configured to receive a respective sub-band noise signal and generate an amplitude modulation signal by modulating an amplitude of the respective sub-band noise signal; and

a phase modulator configured to receive the amplitude modulation signal from the amplitude modulator and generate the subband noise modifying signal by modulating a phase of the amplitude modulation signal to suppress the corresponding subband noise signal.

17. The system of claim 16, wherein the phase modulation of the amplitude modulation signal comprises a phase inversion of the amplitude modulation signal.

18. The system of claim 17, wherein the phase modulation of the amplitude modulation signal comprises compensation for a phase offset of the subband noise signal in propagation from a subband noise sensor to the phase modulator.

19. The system according to any one of claims 1 to 18, wherein:

the noise modification signal comprises the sub-band noise modification signal;

the output module comprises at least two output units, an

Each of the output units is configured to receive one of the sub-band noise modification signals generated by the sub-band noise suppression module and output the received sub-band noise modification signal.

20. The system of any one of claims 1 to 18, wherein the output module is configured to:

receiving the sub-band noise modification signal from the sub-band noise suppression module;

combining the sub-band noise correction signals to generate the noise correction signal; and

and outputting the noise correction signal.

21. The system of any one of claims 1 to 20, wherein the noise comprises ambient noise.

22. The system of claim 21, further comprising:

a residual noise sensor configured to detect residual noise and generate a residual noise signal in response to the detected residual noise, a distance between the residual noise sensor and the output module being shorter than a distance between the sub-band noise sensor and the output module;

a residual noise suppression module configured to receive the residual noise signal and generate a residual noise correction signal to suppress the residual noise.

23. The system of claim 22, wherein:

the output module is further configured to receive the residual noise correction signal and output the residual noise correction signal, or

The system also includes a second output module configured to receive the residual noise correction signal and output the residual noise correction signal.

24. The system according to claim 22 or 23, wherein:

the residual noise signal generated by the residual noise sensor comprises at least two sub-band residual noise signals,

the residual noise modification signal comprises at least two sub-band residual noise modification signals, each of the sub-band residual noise modification signals being configured to suppress one of the sub-band residual noise signals.

25. The system of claim 21, further comprising:

a residual noise sensor configured to detect residual noise and generate a residual noise signal in response to the detected residual noise, a distance between the residual noise sensor and the output module being shorter than a distance between the sub-band noise sensor and the output module; and a feedback module configured to adjust the sub-band noise suppression module according to the residual noise.

26. The system according to any one of claims 1 to 20, wherein:

the sub-band noise sensor is mounted near or inside the output module

The noise includes residual noise.

27. The system according to any one of claims 1 to 6, wherein the sub-band noise signal is an analog signal and the sub-band noise suppression module comprises an analog signal processing component.

28. The system according to any one of claims 1 to 26, wherein the sub-band noise signal is a digital signal and the sub-band noise suppression module comprises a digital signal processing component.

29. The system of any one of claims 1 to 28, wherein the output module comprises an electroacoustic transducer configured to convert the noise modification signal into an audio signal and output the audio signal.

30. The system according to any one of claims 1 to 28, wherein said output module comprises:

a signal processing unit configured to process the noise correction signal; and

an electro-acoustic transducer configured to convert the processed noise correction signal into an audio signal and output the audio signal.

Technical Field

The present application relates generally to noise reduction and, more particularly, to systems and methods for noise reduction using subband noise reduction techniques.

Background

Noise reduction techniques are often used to suppress noise (e.g., unpleasant, loud, or disruptive unwanted sounds). In general, noise may be reduced in a passive manner, e.g., to cancel (or partially cancel) a noise source, to block the propagation of noise, and/or to prevent the user's ear from hearing the noise, etc., or any combination thereof. These noise reduction techniques may be passive and have poor noise reduction in certain states (e.g., when the noise has low frequencies below a threshold frequency). Recently, Active Noise Reduction (ANR) techniques have been used to generate a noise reduction signal (e.g., a signal in phase opposition to the noise to be suppressed) to suppress the noise in an active manner. Conventional ANR devices may utilize full-band noise reduction techniques to suppress noise by generating a single noise correction signal having a covering noise band. Subband decomposition techniques may be used in noise reduction to improve noise reduction. Accordingly, it is desirable to provide systems and methods for noise reduction using sub-band noise reduction techniques.

Disclosure of Invention

The present application provides a noise reduction system. The noise reduction system may include a sub-band noise sensor, at least two sub-band noise suppression modules, and an output module. The sub-band noise sensor may be configured to detect noise and generate at least two sub-band noise signals in response to the detected noise. Each of the sub-band noise signals may have a unique sub-band of the frequency band of the noise. Each of the sub-band noise suppression modules may be configured to receive one of the sub-band noise signals from a sub-band noise sensor and generate a sub-band noise modification signal for suppressing the received sub-band noise signal. The output module may be configured to receive the sub-band noise modification signal and output a noise modification signal for suppressing noise based on the sub-band noise modification signal.

In some embodiments, the sub-band noise sensor may include an acoustoelectric transducer and a sub-band decomposition module. The acoustoelectric transducer may be configured to detect noise and convert the noise into an electrical signal. The sub-band decomposition module may be coupled to the acoustoelectric transducer and configured to decompose an electrical signal into sub-band noise signals.

In some embodiments, the subband decomposition module may include at least two band pass filters, each of the band pass filters having a unique frequency response and configured to generate one of the subband noise signals.

In some embodiments, a first one of the band pass filters has a first frequency response and is configured to generate a first one of the subband noise signals. A second one of the band pass filters has a second frequency response and is configured to generate a second one of the subband noise signals. Wherein the second sub-band noise signal is adjacent to the first sub-band noise signal in the frequency domain among the sub-band noise signals. The first frequency response and the second frequency response may intersect at a frequency point that is proximate to at least one of a half-power point of the first frequency response or a half-power point of the second frequency response.

In some embodiments, the first frequency response of the first band pass filter and the second frequency response of the second band pass filter may have the same frequency bandwidth or different frequency bandwidths.

In some embodiments, the subband noise suppression module may be integrated into the subband decomposition module.

In some embodiments, the sub-band noise sensor may include at least two acoustoelectric transducers and at least two sampling modules. Each of the acoustoelectric transducers has a unique frequency response and is configured to generate a sub-band noise electrical signal by processing the noise, and to sample the received sub-band noise electrical signal to generate one of the sub-band noise signals.

In some embodiments, one of the acoustoelectric transducers may include an acoustic channel assembly and a sound sensitive assembly. The acoustic channel component may be configured to filter noise to generate sub-band noise. The sound sensitive component may be configured to convert sub-band noise to a sub-band noise electrical signal.

In some embodiments, one of the acoustoelectric transducers may convert the noise into a sub-band noise electrical signal.

In some embodiments, a first one of the acousto-electric transducers has a first frequency response and is configured to generate a sub-band noise electrical signal corresponding to a first one of the sub-band noise signals. A second one of the acoustoelectric transducers has a second frequency response and is configured to generate a sub-band noise electrical signal corresponding to a second one of the sub-band noise signals. Wherein the second sub-band noise signal is adjacent to the first sub-band noise signal in the frequency domain among the sub-band noise signals. The first frequency response and the second frequency response intersect at a frequency point that is proximate to at least one of a half-power point of the first frequency response or a half-power point of the second frequency response.

In some embodiments, the first frequency response of the first acoustoelectric transducer and the second frequency response of the second acoustoelectric transducer have the same frequency bandwidth or different frequency bandwidths.

In some embodiments, the frequency band of the sub-band noise signal generated by the sub-band noise sensor may cover the frequency band of the noise.

In some embodiments, at least one of the sub-band noise suppression modules may include a phase modulator and an amplitude modulator. The phase modulator may be configured to receive the respective sub-band noise signal and generate a phase modulated signal by modulating a phase of the respective sub-band noise signal. The amplitude modulator may be configured to receive the phase modulated signal from the phase modulator and to generate the sub-band noise modification signal by modulating an amplitude of the phase modulated signal to suppress the corresponding sub-band noise signal.

In some embodiments, the phase modulation of the respective sub-band noise may include phase inversion of the respective sub-band noise signal and, optionally, compensation for phase offset in propagation of the sub-band noise sensor to the phase modulator.

In some embodiments, at least one of the sub-band noise suppression modules may comprise an amplitude modulator and a phase modulator. The amplitude modulator may be configured to receive the respective sub-band noise signal and generate an amplitude modulation signal by modulating an amplitude of the respective sub-band noise signal. The phase modulator may be configured to receive the amplitude modulation signal from the amplitude modulator and generate the sub-band noise modification signal by modulating a phase of the amplitude modulation signal to suppress the corresponding sub-band noise signal.

In some embodiments, the phase modulation of the amplitude modulation signal may include phase inversion of the amplitude modulation signal and, optionally, compensation for phase offset of the sub-band noise signal in propagation from the sub-band noise sensor to the phase modulator.

In some embodiments, the noise modification signal may comprise a subband noise modification signal. The output module may include at least two output units. Each of the output units may be configured to receive one of the sub-band noise modification signals generated by the sub-band noise suppression module and output the received sub-band noise modification signal.

In some embodiments, the output module may be configured to receive the sub-band noise modification signal from the sub-band noise suppression module. The output module may also be configured to combine the sub-band noise correction signals to generate a noise correction signal. The output module may also be configured to output a noise correction signal.

In some embodiments, the noise may include ambient noise.

In some embodiments, the noise reduction system further comprises a residual noise sensor and a residual noise suppression module. The residual noise sensor may be configured to generate a residual noise signal in response to the detected residual noise. The distance between the residual noise sensor and the output module is shorter than the distance between the sub-band noise sensor and the output module. The residual noise suppression module may be configured to receive a residual noise signal and generate a residual noise correction signal to suppress residual noise.

In some embodiments, the output module may be further configured to receive the residual noise correction signal and output the residual noise correction signal. The system also includes a second output module configured to receive the residual noise correction signal to suppress residual noise.

In some embodiments, the residual noise signal generated by the residual noise sensor may comprise at least two sub-band residual noise signals, and the residual noise modification signal may comprise at least two sub-band residual noise modification signals, each of which may be configured to suppress one of the sub-band noise residual signals.

In some embodiments, the system may include a residual noise sensor and a feedback module. The residual noise sensor may be configured to detect residual noise and generate a residual noise signal in response to the detected residual noise, a distance between the residual noise sensor and the output module being shorter than a distance between the sub-band noise sensor and the output module. The feedback module may be configured to adjust the sub-band noise suppression module according to the residual noise.

In some embodiments, the sub-band noise sensor may be mounted in addition to or within the output module. The noise may include residual noise.

In some embodiments, the sub-band noise signal may be an analog signal and the sub-band noise suppression module may include an analog signal processing component.

In some embodiments, the sub-band noise signal may be a digital signal and the sub-band noise suppression module may include a digital signal processing component.

In some embodiments, the output module may include an electroacoustic transducer configured to convert the noise modification signal into an audio signal and output the audio signal.

In some embodiments, the output module may include a signal processing unit and an electroacoustic transducer. The signal processing unit may be configured to process the noise correction signal. The electroacoustic transducer may be configured to convert the processed noise-corrected signal into an audio signal and output the audio signal.

Additional features of the present application will be set forth in part in the description which follows. Additional features of some aspects of the present application will be apparent to those of ordinary skill in the art in view of the following description and accompanying drawings, or in view of the production or operation of the embodiments. The features of the present application may be realized and attained by practice or use of the methods, instrumentalities and combinations of the various aspects of the specific embodiments described below.

Drawings

The present application will be further described by way of exemplary embodiments. These exemplary embodiments will be described in detail by means of the accompanying drawings. These embodiments are non-limiting exemplary embodiments in which like reference numerals represent similar structures throughout the several views of the drawings, and wherein:

FIG. 1A is a schematic diagram of an exemplary noise reduction system shown in accordance with some embodiments of the present application;

FIG. 1B is a schematic diagram of an exemplary noise reduction system shown in accordance with some embodiments of the present application;

FIG. 2 is a schematic view of an exemplary noise reducer according to some embodiments of the present application;

FIG. 3 is a schematic view of an exemplary noise reducer according to some embodiments of the present application;

FIG. 4 is a schematic diagram of an exemplary sub-band noise sensor shown in accordance with some embodiments of the present application;

figure 5A illustrates an exemplary frequency response of a first band pass filter and an exemplary frequency response of a second band pass filter of a subband decomposition module according to some embodiments of the present application;

FIG. 5B illustrates a frequency response of the first band pass filter of FIG. 5 and another exemplary frequency response of the second band pass filter of FIG. 5 according to some embodiments of the present application;

FIG. 6 is a schematic diagram of an exemplary sub-band noise sensor shown in accordance with some embodiments of the present application;

FIG. 7 is a schematic diagram of an exemplary sub-band noise suppression module shown in accordance with some embodiments of the present application;

FIG. 8 is a schematic diagram of an exemplary phase modulated signal shown in accordance with some embodiments of the present application;

FIG. 9 is a schematic diagram of an exemplary sub-band noise suppression module shown in accordance with some embodiments of the present application;

FIG. 10 is a schematic diagram of an exemplary sub-band noise sensor shown in accordance with some embodiments of the present application;

FIG. 11 is a schematic diagram of an exemplary noise reduction system shown in accordance with some embodiments of the present application;

FIG. 12 is a schematic diagram of an exemplary noise reduction system shown in accordance with some embodiments of the present application;

FIG. 13 is a schematic diagram of an exemplary noise reduction system shown in accordance with some embodiments of the present application;

FIG. 14 is a schematic diagram of an exemplary noise reduction system shown in accordance with some embodiments of the present application; and

FIG. 15 is a schematic diagram of an exemplary noise reduction system shown in accordance with some embodiments of the present application.

Detailed Description

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings used in the description of the embodiments will be briefly introduced below. However, it will be apparent to one skilled in the art that the present application may be practiced without these specific details. In other instances, well known methods, procedures, systems, components, and/or circuits have been described at a relatively high-level, diagrammatic, herein, in order to avoid unnecessarily obscuring aspects of the present application. It will be apparent to those skilled in the art that various modifications to the disclosed embodiments are possible, and that the general principles defined in this application may be applied to other embodiments and applications without departing from the spirit and scope of the application. Thus, the present application is not limited to the described embodiments, but should be accorded the widest scope consistent with the claims.

It is to be understood that the terms "system," "engine," "unit," "module," and/or "block" as used herein are a way of distinguishing between different components, elements, components, parts, or assemblies of different levels in ascending order. However, other words may be substituted by other expressions if they accomplish the same purpose.

It will be understood that when a unit, engine, module or block is referred to as being "on," "connected to," or "coupled to" another unit, engine, module or block, it can be directly on, connected or coupled to or in communication with the other unit, engine, module or block, or intervening units, engines, modules or blocks may be present, unless the context clearly dictates otherwise. In this application, the term "and/or" may include any one or more of the associated listed items or combinations thereof.

The terminology used herein is for the purpose of describing particular examples and embodiments only and is not intended to be limiting. As used herein, the singular forms "a", "an" and "the" may include the plural forms as well, unless the context clearly indicates otherwise. In general, the terms "comprises" and "comprising" merely indicate that steps and elements are included which are explicitly identified, that the steps and elements do not form an exclusive list, and that a method or apparatus may include other steps or elements.

The spatial and functional relationships between elements (e.g., between layers) may be described in various terms, including "connected," engaged, "" interacting, "and" coupled. Unless explicitly described as "direct," when a relationship between a first and a second element is described in the present application, the relationship includes a direct relationship in which no other intermediate element exists between the first and the second element, and an indirect relationship in which one or more intermediate elements exist (spatially or functionally) between the first and the second element. In contrast, when an element is referred to as being "directly" connected, joined, interfaced, or coupled to another element, there are no intervening elements present. In addition, the spatial and functional relationships between elements may be implemented in various ways. For example, the mechanical connection between two elements may include a welded connection, a keyed connection, a pinned connection, an interference fit connection, or the like, or any combination thereof. Other words used to describe relationships between elements should be interpreted in a similar manner (e.g., "between," "and.. between," "adjacent" and "directly adjacent," etc.).

One aspect of the present application relates to a noise reduction system. The noise reduction system may include a sub-band noise sensor, at least two sub-band noise suppression modules, and an output module. The sub-band noise sensor may be configured to detect noise and generate at least two sub-band noise signals in response to the detected noise. Each of the at least two sub-band noise signals has a distinct sub-band of the frequency band of the noise. Each of the sub-band noise suppression modules may be configured to receive one of the sub-band noise signals from the sub-band noise sensor and generate a sub-band noise modification signal for suppressing the received sub-band noise signal. The output module may be configured to receive the sub-band noise correction signal and output a noise correction signal for suppressing noise.

According to some embodiments of the present application, the system may suppress noise using a sub-band noise reduction technique that may reduce noise in at least two sub-bands of a frequency band of the noise. Compared with a full-band noise reduction technology which directly reduces noise in the whole frequency band of noise, the sub-band noise reduction technology can improve the noise reduction effect. In some embodiments, noise reduction systems may be used in various scenarios to suppress various types of noise. For example, the audio broadcasting apparatus may include an ambient noise reduction device and a residual noise reduction device. The ambient noise reduction means is for suppressing ambient noise, and the residual noise reduction means is for suppressing residual noise after suppressing ambient noise. Each or one of the ambient noise reduction means and the residual noise reduction means may be implemented by one or more components of the noise reduction system described above. The combination of the ambient noise reduction means and the residual noise reduction means can effectively suppress unwanted sounds, thereby improving the performance of the audio broadcasting apparatus.

FIG. 1A is a schematic diagram of an exemplary noise reduction system 100A shown in accordance with some embodiments of the present application. The noise reduction system 100A may be configured to suppress or eliminate noise (e.g., unpleasant, loud, or unwanted sounds that are disruptive to hearing). The noise reduction system 100A may be applied to various fields and/or devices, such as headphones (e.g., noise reduction headphones, bone conduction headphones), mufflers, snore-stopping devices, and the like, or any combination thereof. In some embodiments, noise reduction system 100A may be an active noise reduction system that suppresses noise by generating a noise reduction signal (e.g., a signal that is in phase opposition to the noise) for suppressing noise.

As shown in FIG. 1A, the noise reduction system 100A may include an ambient noise reducer 120, a residual noise reducer 150, and an output module 170. In some embodiments, two or more components of noise reduction system 100A may be connected and/or in communication with each other. For example, each of the ambient noise reducer 120 and the residual noise reducer 150 may be electrically connected to the output module 170. As used herein, a connection between two components may include a wireless connection, a wired connection, any other communication connection that may enable the propagation and/or reception of data, and/or any combination of such connections. The wireless connection may include, for example, a bluetooth link, a Wi-Fi link, a WiMax link, a WLAN link, a zigbee link, a mobile network link (e.g., 3G, 4G, 5G, etc.), and the like, or combinations thereof. A wired connection may include, for example, a coaxial cable, a communication cable (e.g., a communication cable), a flexible cable, a spiral cable, a non-metal-sheathed cable, a multi-core cable, a twisted-pair cable, a ribbon cable, a shielded cable, a twisted-pair cable, an optical fiber, a cable, an optical cable, a telephone line, etc., or any combination thereof.

The ambient noise reducer 120 may be configured to suppress the ambient noise 110. For example, as shown in fig. 1A, the ambient noise reducer 120 may detect the ambient noise 110 and generate an ambient noise correction signal 130 for suppressing the ambient noise 110. As used herein, ambient noise 110 may refer to any sound other than a desired sound. For example, the ambient noise 110 may include background sounds (e.g., traffic noise, wind noise, water noise, extraneous speech) that are present when the user wears an audio broadcasting device (e.g., headphones). The ambient noise reduction means 120 may detect the ambient noise 110 when the audio broadcasting device is playing audio (e.g. music) or not playing audio.

In some embodiments, the ambient noise reducer 120 may be configured to suppress the ambient noise 110 according to a full band noise reduction technique or a sub-band noise reduction technique. Full-band noise reduction techniques may generate a single noise-modified signal to suppress noise, the frequency band of the single noise-modified signal covering the frequency band of the original noise. For example, the noise correction signal may be an analog signal or a digital signal having an opposite phase to the noise. The sub-band noise technique may generate at least two sub-band noise modification signals to suppress noise. Each sub-band noise correction signal has a unique sub-band of the noise band (i.e., a band narrower and within the noise band) for suppressing a portion of the noise having the unique sub-band.

In some embodiments, the ambient noise reduction device 120 may include one or more components to implement sub-band noise reduction techniques. For example, the ambient noise reduction device 120 may include a first sub-band noise sensor and at least two first sub-band noise suppression modules. The first sub-band noise sensor may be configured to detect ambient noise 110 and generate at least two sub-band ambient noise signals. The frequency band of each sub-band ambient noise signal may be narrower than and within the frequency band of the ambient noise 110. The frequency bands of the different sub-band ambient noise signals may be different from each other. The first sub-band noise suppression module may be configured to generate at least two sub-band ambient noise modification signals based on the sub-band ambient noise signal. Each sub-band ambient noise modification signal may be an analog signal or a digital signal for suppressing one sub-band ambient noise signal. The sub-band ambient noise correction signal may form the ambient noise correction signal 130 or be processed (e.g., combined) to generate the ambient noise correction signal 130. In some embodiments, the ambient noise reducer 120 may be implemented by a noise reducer 200 having one or more components as shown in FIG. 2.

As shown in fig. 1, the ambient noise modification signal 130 generated by the ambient noise reducer 120 may be sent to an output module 170 for output. The output module 170 may include an electro-acoustic transducer (e.g., speaker, audio player) that may convert the electrical signal to an audio signal to suppress the ambient noise 110. For example, the ambient noise modification signal 130 may be a first synthesized signal of the sub-band ambient noise modification signal. The output module 170 may directly convert the first synthesized signal into an audio signal to output. Alternatively, the output module 170 may include a signal processing unit and an electroacoustic transducer. The signal processing unit may be configured to process the first synthesized signal, and the electroacoustic transducer may be configured to convert the processed first synthesized signal into an audio signal to output. For example only, the first composite signal may be a digital signal. The signal processing unit may convert the first resultant signal into a Pulse Width Modulation (PWM) signal or an analog signal. The electro-acoustic transducer may also convert the PWM signal or the analog signal into sound to be output. In some alternative embodiments, the signal processing unit of the output module 170 may be integrated into the ambient noise reducer 120. The ambient noise reducer 120 may process the first composite signal and send the processed first composite signal to the output module 170 for output.

In some embodiments, the ambient noise modification signal 130 may comprise at least two sub-band ambient noise modification signals as previously described. The output module 170 may comprise at least two output units, each of which may comprise an electroacoustic transducer and optionally a signal processing unit. Each sub-band ambient noise correction signal may be sent in parallel to one output unit for output. As described above, the output manner of the output unit for the sub-band ambient noise correction signal may be similar to the output manner of the output module 170 for the first composite signal of the sub-band ambient noise correction signal.

The audio signal output by the output module 170 to suppress the ambient noise 110 may interfere with the ambient noise 110, wherein the interference may suppress or partially suppress the ambient noise 110, as shown by the dashed line connecting the audio signal output by the output module 170 and the ambient noise 110 in fig. 1A. In some embodiments, residual noise 140 may also be present after the ambient noise 110 is suppressed. The residual noise reducer 150 may be used as a feedback mechanism for the noise reduction system 100A to suppress the residual noise 140. For example, as shown in fig. 1A, the residual noise reduction means 150 may detect the residual noise 140 and generate a residual noise correction signal 160 for suppressing the residual noise 140.

In some embodiments, the residual noise reducer 150 may be configured to suppress the residual noise 140 according to a full band noise reduction technique or a sub-band noise reduction technique as described above. For example, the residual noise reduction means 150 may generate a single residual noise correction signal 160 having the same frequency band as the residual noise 140 and opposite in phase thereto for suppressing the residual noise 140. As another example, residual noise reduction device 150 may include one or more components, such as a second sub-band noise sensor and at least two second sub-band noise suppression modules, to implement sub-band noise reduction techniques. The distance of the second sub-band noise sensor may be shorter than the sensor of the ambient noise reduction apparatus 120 for detecting the ambient noise 110 (e.g., the first sub-band noise sensor as described above), so that the second sub-band noise sensor may detect the residual noise 140. In response to the residual noise 140, the second sub-band noise sensor may generate at least two sub-band residual noise signals, each of which may have a unique sub-band of the frequency band of the residual noise 140. Each second sub-band noise suppression module may be configured to receive one of the sub-band residual noise signals from the second sub-band noise sensor and generate a sub-band residual noise modification signal for suppressing the received sub-band residual noise signal. The sub-band residual noise correction signal may form the residual noise correction signal 160 or be processed (e.g., combined) to generate the residual noise correction signal 160. In some embodiments, the residual noise reducer 150 may be implemented by the noise reducer 200 having one or more components as shown in FIG. 2 and/or the residual noise reducer 150C having one or more components as shown in FIG. 14.

The residual noise correction signal 160 generated by the residual noise reduction apparatus 150 may be sent to the output module 170 for output. The residual noise correction signal 160 may be output in a similar manner as the ambient noise correction signal 130 described above. For example, the output module 170 may convert the residual noise correction signal 160 into an audio signal for suppressing the residual noise 140. The audio signal for suppressing the residual noise 140 may be output together with the above-described ambient noise for suppressing the ambient noise 110. The audio signal for suppressing the residual noise 140 may interfere with the residual noise 140 as shown by a dotted line connecting the audio signal output by the output module 170 and the residual noise 110 in fig. 1A. In some embodiments, the output module 170 may output the ambient noise modification signal 130 and the residual noise reduction device 150, respectively. Alternatively, the ambient noise correction signal 130 and the residual noise correction signal 160 may be combined to generate a second composite signal, which may be further output by the output module 170 to suppress the ambient noise 110 and the residual noise 140.

In some alternative embodiments, rather than generating the residual noise correction signal 160, the residual noise reducer 150 may send a feedback signal to the ambient noise reducer 120 based on the detected residual noise 140. For example, the feedback signal may be generated by a feedback module of the residual noise reduction apparatus 150, which may include information related to the residual noise 140. The ambient noise reduction means 120 may adjust one or more parameters related to the generation of the ambient noise correction signal 130 such that the adjusted ambient noise correction signal 130 may be generated to more effectively suppress the ambient noise 110. As another example, the feedback signal may include instructions for directing the ambient noise reduction device 120 to adjust one or more parameters related to the generation of the ambient noise correction signal 130. More description of the feedback module and/or adjustment of parameters related to the generation of the ambient noise modification signal 130 may be found elsewhere in the application. See, for example, fig. 13 and its associated description.

In some embodiments, the noise reduction system 100A may be applied to an audio broadcasting device. The components of the noise reduction system 100A may be mounted anywhere on the audio broadcasting equipment. For example, the ambient noise reducer 120 or a portion thereof (e.g., a sensor for detecting the ambient noise 110) may be mounted outside of the audio broadcasting apparatus. The output module 170 may be installed in the audio broadcasting apparatus. The output module 170 may be configured to output the noise correction signal and optionally serve as an output component of the audio broadcasting apparatus to output desired audio (e.g., music). The residual noise reducer 150 or a portion thereof (e.g., a sensor for detecting the residual noise 140) may be mounted near or within the output module 170.

FIG. 1B is a schematic diagram of an exemplary noise reduction system 100B shown in accordance with some embodiments of the present application. Noise reduction system 100B is similar to noise reduction system 100A depicted in fig. 1A, except that noise reduction system 100B may include an output module 170 and an additional output module 180. As shown in fig. 1B, the output module 170 may be electrically connected to the ambient noise reducer 120 for outputting the ambient noise modification signal 130. The output module 180 may be electrically connected to the residual noise reduction means 150 for outputting the residual noise correction signal 160.

It should be noted that the above description of noise reduction systems 100A and 100B is intended to be illustrative, and not to limit the scope of the present application. Many alternatives, modifications, and variations will be apparent to those skilled in the art. The features, structures, methods, and other features of the exemplary embodiments described herein may be combined in various ways to obtain additional and/or alternative exemplary embodiments. For example, noise reduction system 100A and/or noise reduction system 100B may include one or more additional components. Additionally or alternatively, one or more components of the noise reduction system 100A and/or the noise reduction system 100B described above may be omitted. For example, one of the ambient noise reducer 120 and the residual noise reducer 150 may be omitted. Additionally, two or more components of noise reduction system 100A and/or noise reduction system 100B may be integrated into a single component. For example only, in the noise reduction system 100B, the output module 170 may be integrated into the ambient noise reducer 120 and/or the output module 180 may be integrated into the residual noise reducer 150.

FIG. 2 is a schematic illustration of an exemplary noise reducer 200 shown according to some embodiments of the present application. The noise reducer 200 may be configured to suppress the noise 210 using sub-band noise reduction techniques as described elsewhere in this application (e.g., fig. 1A and related description).

As shown in fig. 2, the noise reducer 200 may include a sub-band noise sensor 220, at least two sub-band noise suppression modules 230, and a synthesis module 240. The noise reducer 200 may be coupled to the output module 170. The sub-band noise sensor 220 may be configured to detect noise 210 (e.g., the ambient noise 110 or the residual noise 140 described in fig. 1) and generate at least two sub-band noise signals (e.g., the sub-band noise signals S1 through Sm) in response to the detected noise. "m" can be any positive integer greater than 1, such as 5, 10, 15, and the like.

The noise 210 may be an audio signal having a specific frequency band. A sub-band noise signal may refer to a signal having a frequency band that is narrower than and within the frequency band of noise 210. For example, the frequency band of the noise 210 may be 10Hz to 30,000 Hz. The frequency band of the sub-band noise signal may be 100-200HZ, which is within the frequency band of the noise 210. In some embodiments, the combination of the frequency bands of the sub-band noise signals may cover the frequency bands of the noise 210. Additionally or alternatively, at least two of the sub-band noise signals may have different frequency bands. Alternatively, each of the sub-band noise signals may have a unique frequency band that is different from the frequency bands of the other sub-band noise signals. The different sub-band noise signals may have the same frequency bandwidth or different frequency bandwidths. In some embodiments, band overlapping between adjacent sub-band noise signals in the frequency domain may be avoided, thereby improving the noise reduction effect. As used herein, among the sub-band noise signals, two sub-band noise signals whose center frequencies are adjacent to each other may be considered to be adjacent to each other in the frequency domain. More description of the frequency bands of adjacent sub-band noise signals may be found elsewhere in this application. See, for example, fig. 5A and 5B and their associated description.

In some embodiments, the sub-band noise signal generated by sub-band noise sensor 220 may be a digital signal or an analog signal. For purposes of illustration, unless otherwise indicated or evident in context, the present application describes subband noise signals as digital signals, and is not intended to limit the scope of the present application. In the sub-band noise sensor 220, the sub-band noise sensor 220 may include one or more components as shown in fig. 4, which may be configured to convert the noise 210 into an electrical signal and separate the electrical signal into sub-band noise signals. Alternatively, sub-band noise sensor 220 may include one or more components as shown in fig. 6, which may be configured to generate at least two sub-band noise electrical signals by processing noise 210 and sample the sub-band noise electrical signals to generate sub-band noise signals. More description of the sub-band noise sensor 220 may be found elsewhere in this application. See, for example, fig. 4 through 6 and their associated description.

As shown in fig. 2, sub-band noise suppression module 230 may include sub-band noise suppression module 230-1, sub-band noise suppression modules 230-2. In some embodiments, the count (or number) of sub-band noise suppression modules 230 may be equal to the count (or number) of sub-band noise signals generated by sub-band noise sensor 220. Each of the sub-band noise suppression modules 230 may be configured to receive one sub-band noise signal from the sub-band noise sensor 220 and generate a sub-band noise modification signal for suppressing the received sub-band noise signal. For example, as shown in fig. 2, sub-band noise suppression block 230-i (i is a positive integer equal to or less than m) may receive sub-band noise signal Si from sub-band noise sensor 220 and generate sub-band noise correction signal Ci for suppressing sub-band noise signal Si.

In some embodiments, the sub-band noise signals may be transmitted from sub-band noise sensor 220 to sub-band noise suppression module 230 by a parallel transmitter. Alternatively, the sub-band noise signals may be transmitted via a transmitter according to a particular communication protocol used to transmit the digital signals. Exemplary communication protocols may include AES3 (Audio engineering society), AES/EBU (European broadcasting Union)), EBU (European broadcasting Union), ADAT (automatic data accumulator and propagation), I2S (Inter-IC Sound), TDM (time division multiplexing), MIDI (musical instrument digital interface), CobraNet, Ethernet AVB (Ethernet Audio/video Jumper), Dante, ITU (International telecommunication Union) -TG.728, ITU-TG.711, ITU-TG.722, ITU-TG.722.1, ITU-TG.722.1Annex C, AAC (advanced Audio coding) -LD, and the like, or combinations thereof. The digital signal may be propagated in a format including CD (compact disc), WAVE, AIFF (audio exchange file format), MPEG (moving picture experts group) -1, MPEG-2, MPEG-3, MPEG-4, MIDI (musical instrument digital interface), wma (windows Media audio), RealAudio, VQF (transform domain weighted nreleave vector quantization), AMR (adaptive multi-rate), APE, FLAC (free lossless audio codec), AAC (advanced audio coding), etc., or a combination thereof. In some alternative embodiments, the sub-band noise signal may be processed into a single channel signal using frequency division multiplexing or the like and sent to sub-band noise suppression module 230.

In some embodiments, sub-band noise suppression module 230-i may perform phase modulation and/or amplitude modulation on sub-band noise signal Si to generate a corresponding sub-band noise modification signal Ci. In one embodiment, the phase modulation and amplitude modulation of the subband noise signal Si may be performed sequentially or simultaneously. For example, the sub-band noise suppression block 230-i may first perform phase modulation on the sub-band noise signal Si to generate a phase modulated signal, and then perform amplitude modulation on the phase modulated signal to generate a corresponding sub-band noise modification signal Ci. The phase modulation of the sub-band noise signal Si may include phase inversion of the sub-band noise signal Si. Alternatively, in some embodiments, the noise 210 may be phase shifted (or shifted) during propagation from a location at the sub-band noise sensor 220 to a location at the output module 170 (e.g., from a location external to the audio broadcasting device to a location at a speaker within the audio broadcasting device). The phase modulation of the sub-band noise signal Si may also include compensation for phase shifts that occur during signal propagation of the sub-band noise signal Si. Alternatively, the subband noise suppressing block 230-i may first perform amplitude modulation on the subband noise signal Si to generate an amplitude modulation signal, and then perform phase modulation on the amplitude modulation signal to generate the subband noise modifying signal Ci. More description of the sub-band noise suppression block 230-i may be found elsewhere in this application. See, for example, fig. 7-9 and their associated description.

The synthesis module 240 may be configured to combine the sub-band noise correction signals to generate a noise correction signal, as shown in fig. 2. The combining module 240 may include any component that may combine at least two signals. For example, the synthesis module 240 may generate a mixed signal (i.e., a noise-corrected signal) according to a signal combining technique, such as a frequency division multiplexing technique. In some alternative embodiments, the synthesis module 240 may be a stand-alone component or part of another component (e.g., the output module 170) in addition to the noise reducer 200. Alternatively, as shown in fig. 3, the synthesis module 240 may be omitted and the sub-band noise correction signals may be sent in parallel to the output module 170 for output.

The output module 170 may be configured to receive the noise correction signal from the synthesis module 240. The output module 170 may output the noise correction signal in a manner similar to the ambient noise correction signal 130 described in fig. 1A. For example, the output module 170 may convert the noise correction signal into an audio signal for output, or process the noise correction signal and convert the processed noise correction signal into an audio signal for output.

One or more components of the noise reduction system 100A (or the noise reduction system 100B) may be implemented separately or collectively on one or more components of the noise reducer 200. For example, the ambient noise reducer 120 may be implemented by one or more components of the noise reducer 200. The sub-band noise sensor 220 of the ambient noise reduction device 120 may be spaced apart from the output module 170 by a distance greater than a threshold distance to detect the ambient noise. For example only, the sub-band noise sensor 220 may be installed outside the audio broadcasting apparatus and the output module 170 may be installed inside the audio broadcasting apparatus. Additionally or alternatively, the residual noise reducer 150 may be implemented by one or more components of the noise reducer 200. The sub-band noise sensor 220 of the residual noise reduction apparatus 150 may be installed near or inside the output module 170 (e.g., within a threshold distance from the output module 170) to detect residual noise in the noise reduction. For example, the sub-band noise sensor 220 and the output module 170 may both be installed within the audio broadcasting apparatus and be close to each other.

FIG. 3 is a schematic diagram of an exemplary noise reducer 300 shown in accordance with some embodiments of the present application. The noise reducer 300 may be similar to the noise reducer 200, except for certain components or features. As shown in fig. 3, the output module 170 may include at least two output units 170-1, 70-2. The subband-noise modifying signals generated by the subband-noise suppressing block 230 may be transmitted to the output unit 170 in parallel without being combined. Each output unit may be configured to receive one sub-band noise modification signal and output the received sub-band noise modification signal. In some embodiments, similar to the noise reducer 200, the noise reducer 300 may be used to implement one or more components of the noise reduction system 100A (or the noise reduction system 100B), such as the ambient noise reducer 120 and/or the residual noise reducer 150.

It should be noted that the above description of the noise reducer 200 and 300 is intended to be illustrative, and not limiting, of the scope of the present application. Many alternatives, modifications, and variations will be apparent to those skilled in the art. The features, structures, methods, and other features of the exemplary embodiments described herein may be combined in various ways to obtain additional and/or alternative exemplary embodiments. For example, the noise reducer 200 and/or the noise reducer 300 may include one or more additional components. Additionally or alternatively, one or more components of the noise reducer 200 and/or the noise reducer 300 described above, such as the synthesis module 240, may be omitted. Additionally, two or more components of the noise reducer 200 and/or the noise reduction system 300 may be integrated into a single component. For example only, the synthesis module 240 and/or the output module 170 of the noise reducer 200 may be integrated into the subband noise suppression module 230 of the noise reducer 200.

Fig. 4 is a schematic diagram of an exemplary sub-band noise sensor 220A shown in accordance with some embodiments of the present application. Sub-band noise sensor 220A may be an exemplary embodiment of sub-band noise sensor 220 as described in fig. 2. As shown in FIG. 4, sub-band noise sensor 220A may include an acoustoelectric transducer 410 and a sub-band decomposition module 420 coupled to acoustoelectric transducer 410.

The acoustoelectric transducer 410 may be configured to detect the noise 210 and convert the noise 210 into an electrical signal. The frequency band of the electrical signal may be the same (or substantially the same) as the frequency band of the noise 210. The acoustoelectric transducer 410 may include a microphone, a hydrophone, an acoustic modulator (AOM), or any other device that may convert an audio signal into an electrical signal, or any combination thereof.

The sub-band decomposition module 420 may be configured to divide the electrical signal into at least two sub-band noise signals (e.g., sub-band noise signals S1 through Sm). In some embodiments, the subband decomposition module 420 may include at least two band pass filters. Each band pass filter may have a unique frequency response and may generate one of the sub-band noise signals by processing the electrical signal. The frequency response of a band-pass filter may refer to a quantitative measure of the output spectrum (i.e., the corresponding sub-band noise signal) it produces in response to an input (i.e., an electrical signal). For example, the frequency response of the band pass filter may include a center frequency, a frequency bandwidth, a cutoff frequency, and the like, or any combination thereof.

In some embodiments, the combination of the frequency bands of the sub-band noise signals may cover the frequency bands of the noise 210. The frequency bandwidths of the different sub-band noise signals may be the same or different from each other. Additionally or alternatively, band overlap between adjacent sub-band noise signals in the frequency domain may be avoided. To this end, in some embodiments, the frequency responses of two band pass filters that generate a pair of adjacent subband noise signals may intersect at a particular frequency point that satisfies a particular condition.

For purposes of illustration, fig. 5A shows an exemplary frequency response 510 of a first band pass filter and an exemplary frequency response 520 of a second band pass filter according to some embodiments of the present application. Fig. 5B illustrates a frequency response 510 of a first band pass filter and another exemplary frequency response 530 of a second band pass filter according to some embodiments of the present application. The first bandpass filter may be configured to process the electrical signal generated by the acoustoelectric transducer 410 to generate a first sub-band noise signal of the sub-band noise signals. The second band pass filter may be configured to process the electrical signal generated by the acoustoelectric transducer 410 to generate a second sub-band noise signal of the sub-band noise signals. In the sub-band noise signal, the second sub-band noise signal may be adjacent to the first sub-band noise signal in a frequency domain.

In some embodiments, the frequency responses of the first and second band pass filters may have the same frequency bandwidth. For example, as shown in FIG. 5A, the frequency response 510 of the first bandpass filter has a lower half-power point f₁Upper half power point f₂And a center frequency f₃. As used herein, a half-power point of a certain frequency response may refer to a frequency point with a certain power attenuation (e.g., -3 dB). The frequency bandwidth of the frequency response 510 may be equal to f₂And f₁The difference between them. The frequency response 520 of the second band-pass filter has a lower half-power point f₂Upper half power point f₄And a center frequency f₅. The frequency bandwidth of frequency response 520 may be equal to f₄And f₂The difference between them. The frequency bandwidths of the first and second band-pass filters may be equal to each other.

Alternatively, the frequency responses of the first and second band pass filters may have different frequency bandwidths. For example, as shown in FIG. 5B, the frequency response 530 of the second bandpass filter has a lower half-power point f₂Upper half power point f₇(greater than f)₄) And a center frequency f₆. The frequency bandwidth of the frequency response 530 of the second band-pass filter may be equal to f₇And f₂The difference between which may be greater than the frequency bandwidth of the frequency response 510 of the first band pass filter. This may cause the subband decomposition module 420 to use fewer band pass filters to generate at least two subband noise signals to cover the frequency band of the noise 210.

In some embodiments, the frequency responses of the first and second bandpass filters may intersect at a particular frequency point. In some embodiments, the particular frequency point at which the frequency responses of the first and second bandpass filters intersect may be near the half-power point of the frequency response of the first bandpass filter and/or the half-power point of the frequency response of the second bandpass filter. Taking fig. 5A as an example, the frequency response 510 and the frequency response 520 are at the upper half-power point f of the frequency response 510₂Is also the lower half-power point of the frequency response 520. As used herein, a frequency point may be considered to be close to a half-power point if the power level difference between the frequency point and the half-power point is not greater than a threshold (e.g., 2 dB). In this case, there may be less energy loss or overlap in the frequency responses of the first and second bandpass filters, which may result in the frequency responses of the first and second bandpass filtersWith appropriate overlap ranges occurring therebetween. In some embodiments, the overlap range may be considered relatively small when the frequency responses intersect at frequency points where the power levels are greater than-5 dB and/or less than-1 dB. In some embodiments, the center frequency and/or bandwidth of the frequency responses of the first and second band pass filters may be adjusted to make the range of overlap between the frequency responses of the first and second band pass filters narrower or appropriate to avoid band overlap between the first and second sub-band noise signals. In some embodiments, the power level fluctuation of the frequency response of the sub-band decomposition module 420 may be in the range of 1 dB.

It should be noted that the examples shown in fig. 5A and 5B are intended to illustrate, but not to limit the scope of the present application. Many variations and modifications may be made by one of ordinary skill in the art in light of the teachings herein. However, such changes and modifications do not depart from the scope of the present application. For example, one or more parameters of the frequency response of the first and/or second bandpass filters (e.g., frequency bandwidth, upper half-power point, lower half-power point, and/or center frequency) may be variable.

In some embodiments, the band pass filters of the subband decomposition module 420 may include butterworth filters, chebyshev filters, elliptic filters, or the like, or any combination thereof. The slope of the frequency response edge of a band pass filter may be associated with the type and/or order of the band pass filter. For example, the slope of an edge of a butterworth filter having a particular order may be greater than the slope of a chebyshev filter having the same order. The slope of the edge of a chebyshev filter having a particular order may be greater than the slope of an elliptic filter having the same order. For a particular band pass filter having a center frequency, the slope of the edge of the frequency response of the band pass filter may increase with the order of the band pass filter. In some embodiments, the type of band pass filter of the subband decomposition module 420 may be selected according to the frequency band of the noise 210 to be suppressed. For example, to suppress noise having a narrow bandwidth (e.g., a frequency bandwidth less than a first threshold bandwidth), such as low frequency noise or high frequency noise having a narrow bandwidth, a band pass filter having a high order (e.g., an order greater than a threshold order) and a narrow bandwidth (e.g., a frequency bandwidth less than a second threshold bandwidth) may be used. The first and second threshold bandwidths may be the same as or different from each other.

In some embodiments, the band pass filter of the subband decomposition module 420 may be a finite impulse response filter where the impulse response is of finite duration, or an infinite impulse response filter that depends linearly on a finite number of input samples and a finite number of previous filter outputs.

In some embodiments, the sub-band noise signals generated by the sub-band decomposition module 420 may be output in parallel (e.g., over at least two cables) for further processing. For example, each band pass filter of the subband decomposition module 420 may be electrically connected to a subband noise suppression module (e.g., the subband noise suppression module 230), wherein the subband noise signal generated by the band pass filter may be transmitted to the connected subband noise suppression module for generating a corresponding subband noise modification signal. Alternatively, the sub-band noise signal may be processed using techniques such as frequency division multiplexing to generate a single channel signal and output for further processing. In some embodiments, at least two sub-band noise suppression modules may be integrated into the sub-band decomposition module 420. The integrated sub-band decomposition module may generate a sub-band noise signal and also generate at least two sub-band noise modification signals for suppressing the sub-band noise signal. More description of the integrated subband decomposition module may be found elsewhere in this application. See, for example, fig. 10 and its associated description.

It should be noted that the above description of sub-band noise sensor 220A is intended to be illustrative, and not to limit the scope of the present application. Many alternatives, modifications, and variations will be apparent to those skilled in the art. The features, structures, methods, and other features of the exemplary embodiments described herein may be combined in various ways to obtain additional and/or alternative exemplary embodiments. For example, sub-band noise sensor 220A may include one or more additional components. Additionally or alternatively, one or more components of the sub-band noise sensor 220A described above may be omitted. As another example, two or more components of sub-band noise sensor 220A may be integrated into a single component.

Fig. 6 is a schematic diagram of an exemplary sub-band noise sensor 220B shown in accordance with some embodiments of the present application. Sub-band noise sensor 220B may be an exemplary embodiment of sub-band noise sensor 220, as described in fig. 2. The sub-band noise sensor 220B may be configured to detect the noise 210 and generate at least two sub-band noise signals (e.g., sub-band noise signals S1 through Sm) in response to the detected noise 210.

As shown in FIG. 6, sub-band noise sensor 220B may include at least two acoustoelectric transducers 610 (e.g., acoustoelectric transducers 610-1 through 610-m) and at least two sampling modules 620 (e.g., sampling modules 620-1 through 620-m). Each of the acoustic-electric transducers 610 may have a unique frequency response and be configured to generate a sub-band noise electrical signal by processing the noise 210. The sub-band noise electrical signal generated by the acoustoelectric transducer 610 may be an analog signal. Each of the sampling modules 620 may be configured to receive one of the sub-band noise electrical signals and sample the received sub-band electrical signal to generate one of the sub-band noise signals (i.e., a digital signal).

In some embodiments, the count (or number) of the acoustoelectric transducers 610 and the count (or number) of the sampling module 620 may both be equal to the count (or number) (i.e., m) of the sub-band noise signals. The value of m may be associated with the frequency band of the noise 210 and the frequency band of the generated sub-band noise signal. For example, a number of acoustoelectric transducers 610 may be used such that the combination of frequency bands of the sub-band noise signals may cover the frequency band of the noise 210. Additionally or alternatively, band overlap between adjacent ones of the sub-band noise signals may be avoided.

In some embodiments, the acoustic-to-electric transducer 610 may include an acoustic channel assembly and a sound sensitive assembly. The acoustic channel components may form a path through which an audio signal (e.g., noise 210) is propagated to the sound-sensitive components. For example, the acoustic channel assembly may include one or more chamber structures, one or more conduit structures, or the like, or combinations thereof. The sound sensitive component may convert an audio signal (e.g., the original noise 210 or processed noise after passing through the acoustic channel component) passing from the acoustic channel component into an electrical signal. For example, the sound sensitive component 420 may include a diaphragm, a plate, a cantilever, and the like. Taking a diaphragm as an example, the diaphragm may be used to convert a sound pressure change caused by an audio signal on the surface of the diaphragm into mechanical vibration of the diaphragm. The sound sensitive member may be made of one or more materials including, for example, plastic, metal, piezoelectric material, etc., or any composite material.

In one embodiment, the frequency response of the acoustoelectric transducer 610 may be associated with an acoustic structure of an acoustic channel assembly of the acoustoelectric transducer 610. For example, the acoustic channel components of the acoustoelectric transducer 610-i may have a particular acoustic structure that may process the noise 210 before the noise 210 reaches the sound sensitive components of the acoustoelectric transducer 610-i. In some embodiments, the acoustic structure of the acoustic channel assembly may have a particular acoustic resistance, such that the acoustic channel assembly may act as a filter that filters the noise 210 to generate sub-band noise. The sound sensitive components of the acoustoelectric transducer 610-i may convert the sub-band noise into a sub-band noise electrical signal Ei.

In some embodiments, the acoustic impedance of the acoustic structure may be set according to the frequency band of the noise 210. In some embodiments, the acoustic structure comprising primarily the chamber structure may function as a high pass filter, while the acoustic structure comprising primarily the conduit structure may function as a low pass filter. For example only, the acoustic channel assembly may have a lumen structure. The lumen structure may be a combination of a sound volume and an acoustic mass in series, which may form an inductor-capacitor (LC) resonant circuit. If an acoustically resistive material is used in the lumen structure, a resistor-inductor-capacitor (RLC) series loop can be formed and the acoustic resistance of the RLC series loop can be determined according to equation (1) below:

wherein Z refers to the acoustic impedance of the acoustic channel assembly, ω refers to the angular frequency of the lumen tube structure, j refers to the imaginary number of cells, M_aRefers to soundMass, C_aIs referred to as sound volume, R_aRefers to the acoustic resistance of the RLC series loop.

The lumen structure may be used as a band pass filter (denoted F1). Can be adjusted by adjusting the acoustic resistance R_aTo adjust the bandwidth of the band pass filter F1. Can be adjusted by adjusting the acoustic mass M_aAnd/or acoustic capacitance C_aTo adjust the center frequency omega of the band-pass filter F1₀. For example, the center frequency ω of the band-pass filter F1₀Can be determined according to the following equation (2):

in one embodiment, the frequency response of the acoustoelectric transducer 610 may be correlated to a physical property (e.g., material, structure) of a sound-sensitive component of the acoustoelectric transducer 610. A sound sensitive component with a particular physical characteristic may be sensitive to a certain frequency band of the noise 210. For example, mechanical vibration of one or more elements in the sound-sensitive component may cause a change in an electrical parameter of the sound-sensitive component. The sound sensitive component may be sensitive to a certain frequency band of the audio signal. The frequency band of the audio signal may cause a corresponding change in an electrical parameter of the sound sensitive component. In other words, the sound sensitive component may act as a filter that processes the sub-bands of the audio signal. In some embodiments, the noise 210 may propagate through the acoustic channel assembly to the sound sensitive assembly without (or substantially without) being filtered by the acoustic channel assembly. The physical characteristics of the sound sensitive component may be adjusted such that the sound sensitive component may act as a filter for filtering the noise 210 and converting the filtered noise into sub-band noise electrical signals.

For example only, the sound sensitive component may include a diaphragm, which may function as a band pass filter (denoted F2). Center frequency ω 'of band-pass filter F2'₀The following can be determined from equation (3):

wherein M is_mIs the mass of the diaphragm, K_mRefers to the elastic coefficient, R, of the diaphragm_mRefers to the damping of the diaphragm. Can be adjusted by adjusting R_mTo adjust the bandwidth of the band pass filter F2. The center frequency ω 'of the band-pass filter F2 may be adjusted by adjusting the mass of the diaphragm and/or the elastic coefficient of the diaphragm'₀。

As described above, the acoustic channel components or sound sensitive components of the acoustoelectric transducer 610 may be used as filters. The frequency response of the acoustoelectric transducer 610 may be modified by modifying a parameter (e.g., R) of the acoustic channel assembly_a、M_aAnd/or C_a) Or a sound-sensitive component (e.g. K)_mAnd/or R_m) Is adjusted. In some alternative embodiments, the acoustic channel component and the sound sensitive component may together act as a filter. By modifying the parameters of the acoustic channel assembly and the sound sensitive assembly, the frequency response of the combination of the acoustic channel assembly and the sound sensitive assembly can be adjusted accordingly. More description of ACOUSTIC channel components and/or sound sensing components for use as bandpass filters may be found, for example, in PCT application No. PCT/CN2018/105161 entitled "SIGNAL PROCESSING DEVICE HAVING MULTIPLE ACOUSTIC-ELECTRIC transmission," the contents of which are incorporated herein by reference.

In one embodiment, the acoustic-electric transducer 610 may have a frequency response such that the frequency band of the sub-band noise signal generated by the sub-band noise sensor 220B may cover the frequency band of the noise 210 and/or may avoid frequency band overlap between adjacent sub-band noise signals. To this end, in some embodiments, the characteristics of the frequency response of the acoustic transducer 610 corresponding to adjacent flat band noise signals may be the same as or similar to the characteristics of the band pass filter generating adjacent sub-band noise signals described in fig. 4.

For example, in the acoustoelectric transducers 610, a first acoustoelectric transducer having a first frequency response may generate a sub-band noise electrical signal corresponding to a first one of the sub-band noise signals. A second acoustoelectric transducer having a second frequency response may generate a sub-band noise electrical signal corresponding to a second sub-band noise signal adjacent to the first sub-band noise signal in the frequency domain. The first frequency response and the second frequency response may intersect at a frequency point that is close to the half-power point of the first frequency response and/or the half-power point of the second frequency response. For example only, the first frequency response of the first acoustoelectric transducer may be similar to the frequency response 510 of the first band pass filter shown in fig. 5A and 5B. The second frequency response of the second acoustoelectric transducer may be similar to the frequency response 520 of the second band-pass filter shown in fig. 5A or the frequency response 530 of the second band-pass filter shown in fig. 5B.

In one embodiment, the acoustoelectric transducer 610 may transmit the generated sub-band noise electrical signal to the sampling module 620 through one or more transmitters. Exemplary transmitters may be coaxial cables, communication cables (e.g., communication cables), flexible cables, spiral cables, non-metal-sheathed cables, multi-core cables, twisted-pair cables, ribbon cables, shielded cables, twinax cables, optical fibers, and the like, or combinations thereof. In some embodiments, the sub-band noise electrical signal may be transmitted to sampling module 620 through at least two sub-band transmitters connected in parallel. Each of the at least two sub-band transmitters may be connected to the acoustoelectric transducer 610 and transmit the sub-band noise electrical signal generated by the acoustoelectric transducer 610 to a respective sampling module 620. Alternatively, the sub-band noise electrical signal may be processed into a single channel signal using frequency division multiplexing or the like and transmitted to the sampling module 620 via a single transmitter.

In some embodiments, the sampling module 620 may sample the sub-band noise electrical signal using a particular sampling frequency. In some embodiments, the sampling frequency of different sampling modules 620 may be the same. For example, a certain sub-band noise electrical signal may have the largest center frequency among all sub-band noise electrical signals, and the sampling frequency of each sampling module 620 may be greater than twice the highest frequency in the frequency band of the sub-band noise electrical signal. This may avoid signal distortion and frequency aliasing of the subband-noise signals generated by the sampling module 620. However, using a high sampling frequency (e.g., a sampling frequency above a threshold frequency) may take more processing load and/or time.

Alternatively, the sampling frequency of different sampling modules 620 may be different depending on the frequency band of the sub-band noise electrical signal to be sampled. For example, the sampling frequency of the sampling module 620-i may be greater than twice the highest frequency in the frequency band of the sub-band noise electrical signal Ei. In some embodiments, the sampling module 620-i may sample the sub-band noise electrical signal Ei according to a band-pass sampling technique. For example, the sampling frequency of the sampling module 620-i may be no less than twice the frequency bandwidth of the sub-band noise electrical signal Ei and/or no greater than four times the frequency bandwidth of the sub-band noise electrical signal Ei. For another example, assume that the frequency band of the subband noise electric signal Ei is (f)_L，f_H) Sampling frequency f of sub-band noise electric signal Ei_sCan be determined according to the following equation (4):

wherein n may be f such that_sIs equal to or greater than 2 (f)_H-f_L) Is the largest integer of (a). Using a band-pass sampling technique instead of a wideband sampling technique or a low-pass sampling technique, the sampling module 620-i can sample the sub-band noise electrical signal Ei with a relatively low sampling frequency, thereby reducing the difficulty and cost of the sampling process and improving the sampling quality.

In some embodiments, the sub-band noise signals generated by the sampling module 620 at different sampling frequencies may have different sampling periods. At least two sub-band noise suppression modules (e.g., sub-band noise suppression module 230) may receive sub-band noise signals from sub-band noise sensor 220B and generate at least two sub-band noise modification signals. The sub-band noise modification signals may have different sampling periods. According to some embodiments described elsewhere in this application (e.g., fig. 2 and related description), it may be desirable to combine the sub-band noise correction signals to generate the noise correction signal. The subband noise modifying signal may be up-sampled or down-sampled before combining, so that the sampling period of the subband noise modifying signal may be adjusted to the same value.

It should be noted that the above description of sub-band noise sensor 220B is intended to be illustrative, and not to limit the scope of the present application. Many alternatives, modifications, and variations will be apparent to those skilled in the art. The features, structures, methods, and other features of the exemplary embodiments described herein may be combined in various ways to obtain additional and/or alternative exemplary embodiments. For example, one or more components of the sub-band noise sensor 220B described above may be omitted. In some embodiments, the acoustoelectric transducer 610 may directly generate a sub-band noise signal in the form of a digital signal by processing the noise 210, and the sampling module 620 may be omitted. Additionally or alternatively, sub-band noise sensor 220B may include one or more additional components.

Fig. 7 is a schematic diagram of an exemplary sub-band noise suppression module 700 shown in accordance with some embodiments of the present application. The subband noise suppression block 700 may be an exemplary embodiment of the subband noise suppression block 230-i depicted in fig. 2 and 3. Sub-band noise suppression module 700 may be configured to receive a sub-band noise signal S from a sub-band noise sensor (e.g., sub-band noise sensor 220)_i(n) and generating a subband noise signal S for suppressing_i(n) subband noise corrected signal A_tS′_i(n)。A_tMay refer to an amplitude attenuation factor associated with the noise to be suppressed (e.g., noise 210).

As shown in fig. 7, the sub-band noise suppression module 700 may include a phase modulator 710 and an amplitude modulator 720. The phase modulator 710 may be configured to receive the sub-band noise signal S_i(n) and carrying a noise signal S by the counter-rotor_i(n) to generate a phase modulated signal S'_i(n) of (a). For example, as shown in FIG. 8, the phase modulation signal S'_i(n) the subband noise signal S can be inverted_iThe phase of (n). In some embodiments, the noise is derived from generating a sub-band noise signal S_iIn the propagation of the location of the sub-band noise sensor of (n) to a location at an output module (e.g., output module 170) or a portion thereof (e.g., output unit), the phase of the noise may shift (or shift). In some embodiments, the phase offset may be ignored. Phase modulationThe controller 710 may simply pass the sub-band noise signal S_i(n) performing phase inversion to generate a phase modulation signal S'_i(n) of (a). If the frequency of the sound is below the cut-off frequency of the external ear canal, the sound may propagate in the external ear canal as a plane wave. For purposes of illustration, the external ear canal can be considered as a tubular duct having a radius, the cut-off frequency of which can be determined according to the following equation (5):

wherein f is_cRefers to the cut-off frequency of the external auditory canal, c₀Refers to the speed of sound, and r refers to the radius of the external auditory canal. For example, if the speed of sound c₀Equal to 340 meters/second, radius equal to 3.5 millimeters (mm), cutoff frequency f_cMay be approximately equal to 28.4 kilohertz (kHZ). Any sound with a frequency below 28.4kHz can propagate in the external ear canal as plane waves. In general, the wavelength of the noise may be much greater than the length of the external auditory canal (e.g., 25 mm). For example only, the wavelength of the noise at a frequency of 3kHz may be approximately equal to 113mm, which is approximately four times the length of the external ear canal. If the noise is propagated unidirectionally in the form of a plane wave when propagating from the position of the sub-band noise sensor to the position of the output block (or a part thereof), the phase shift during propagation may be small (e.g., less than a threshold), the phase modulation signal S is generated_iThe phase shift can be ignored for (n).

Amplitude modulator 720 may be configured to receive phase modulated signal S'_i(n) and modulating the phase modulation signal S'_i(n) generating a correlation modulation signal A_tS’_i(n) of (a). In one embodiment, the amplitude of the noise may be attenuated during propagation from the location at the sub-band noise sensor to the location at the output module (or a portion thereof). The amplitude attenuation coefficient a can be determined_tTo measure the amplitude attenuation of the noise during propagation. Amplitude attenuation coefficient A_tMay be related to one or more factors, e.g. the material and/or structure of the acoustic channel assembly along which the noise propagatesA position of the sub-band noise sensor relative to the output module (or a portion thereof), etc., or any combination thereof. In some embodiments, the amplitude attenuation coefficient A_tMay be a default setting for the noise reduction system 100A (or 100B) or may have been previously determined by actual or simulated experimentation. By way of example only, the amplitude attenuation coefficient A_tMay be determined by comparing the amplitude of the audio signal in the vicinity of the sub-band noise sensor (e.g., before it enters the audio broadcasting device) with the amplitude after the audio signal is delivered to the location at the output module. In some alternative embodiments, the amplitude attenuation of the noise may be ignored, for example, if the amplitude attenuation during noise propagation is less than a threshold and/or the amplitude attenuation factor A_tSubstantially equal to 1. In this case, the signal S 'is phase-modulated'_i(n) may be designated as a subband noise signal S_i(n) the subband noise corrected signal.

In some embodiments, a noise reducer (e.g., noise reducer 200, noise reducer 300) may include at least two sub-band noise suppression modules 230. Each of the sub-band noise suppression modules 230 may have the same structure as or a similar structure to the sub-band noise suppression module 700 shown in fig. 7, and is configured to generate a corresponding sub-band noise modification signal. At least two sub-noise correction signals may be combined into one noise correction signal s (n) according to the following equation (6):

fig. 9 is a schematic diagram of an exemplary sub-band noise suppression module 900 shown in accordance with some embodiments of the present application. The subband noise suppression block 900 may be an exemplary embodiment of the subband noise suppression block 230-i, as described in fig. 2 and 3. The sub-band noise suppression module 900 may be similar to the sub-band noise suppression module 700 except that the phase modulator 710 of the sub-band noise suppression module 900 may be configured to modulate the sub-band noise signal S_i(n) signal S with noise in the propagation process_iThe phase shift of (n) is taken into account.

By way of example only, the sub-band noise signal S_iThe phase of (n) may be phase offset during its propagation from the location of the sub-band noise sensor (e.g., sub-band noise sensor 220) to the location of the output module (e.g., output module 170) or a portion thereof (e.g., output unit)Phase shiftThe following can be determined from equation (7):

wherein f is₀May refer to the subband noise signal S_iThe center frequency of (n), c, may refer to the speed of sound. Taking the noise reducer 200 as an example, the noise 210 to be reduced may be received from an acoustic source. If the noise 210 is a near-field signal, Δ d may refer to a difference between a distance from the acoustic source to the sub-band noise sensor 220 and a distance from the acoustic source to the output module 170 (or an output unit thereof). If the noise 210 is a far-field signal, Δ d may be equal to dcos θ, where d may refer to a distance between the sub-band noise sensor 220 and the output module 170 (or output unit), and θ represents an angle between a sound source and the sub-band noise sensor 220 or an angle between a sound source and the output module 170 (or output unit 170). Phase shift according to equation (6)May be increased with Δ d and f₀Is increased.

To compensate for phase offsetPhase modulator 710 may modulate the sub-band noise signal S_i(n) performing phase inversion and phase compensation to generate a phase modulation signal. In some embodiments, phase modulator 710 may include an all-pass filter. Filter of all-pass filterThe function may be expressed as h (w), where w represents angular frequency. In an ideal case, the magnitude response | h (w) of the all-pass filter may be equal to 1, and the phase response of the all-pass filter may be equal to the phase shiftThe all-pass filter can filter the sub-band noise signal S_i(n) delaying Δ T in time domain to perform phase compensation, Δ T may be determined according to the following equation (8):

in this case, the phase modulator 710 may modulate the sub-band noise signal S_i(n) phase inversion and phase compensation are performed to generate a phase modulation signal S'_i(n-. DELTA.T), as shown in FIG. 9. The amplitude modulator 720 may also be based on the amplitude attenuation factor A described in FIG. 7_tModulating phase modulation signal S'_i(n- Δ T) to generate a signal S for suppressing sub-band noise_i(n) subband noise corrected signal (i.e., A)_tS’_i(n-ΔT))。

In some embodiments, the noise reducer may include at least two sub-band noise suppression modules 230. Each of the sub-band noise suppression modules 230 may have the same or similar structure as the sub-band noise suppression module 900 shown in fig. 9 and is configured to generate a corresponding sub-band noise modification signal. The at least two sub-noise correction signals may be combined into one noise correction signal S' (n) according to the following equation (9):

it should be noted that the above description of fig. 7 and 9 is intended to be illustrative, and not to limit the scope of the present application. Many alternatives, modifications, and variations will be apparent to those skilled in the art. The features, structures, methods, and other features of the exemplary embodiments described herein may be combined in various ways to obtain additional and/or alternative exemplary embodiments. For example, sub-band noise suppression modules 700 and/or 900 may include one or more additional components. Additionally or alternatively, one or more components of the subband noise suppression modules 700 and/or 900 described above, such as the amplitude modulator 702, may be omitted.

In some alternative embodiments, the sub-band noise signal S_i(n) may be sent to amplitude modulator 720 for phase modulation and then to phase modulator 710 for phase modulation. For example, the amplitude modulator 720 may be based on an amplitude attenuation factor A_tAn amplitude modulation signal is generated and phase modulation (e.g., phase inversion and optional phase compensation) is performed on the amplitude modulation signal to generate a corresponding subband noise correction signal.

Fig. 10 is a schematic diagram of an exemplary sub-band noise sensor 220C shown in accordance with some embodiments of the present application. Sub-band noise sensor 220C may be an exemplary embodiment of sub-band noise sensor 220A as described in fig. 4. A sub-band noise suppression module (e.g., sub-band noise suppression module 230) may be integrated into sub-band noise sensor 220C such that sub-band noise sensor 220C may simultaneously implement the functionality of both sub-band noise sensor 220A and sub-band noise suppression module. In other words, the sub-band noise sensor 220C may be configured to detect the noise 210 to generate at least two sub-band noise signals and at least two sub-band noise modification signals for modifying the sub-band noise signals.

As shown in fig. 10, sub-band noise sensor 220C may include an acoustoelectric transducer 410 and a sub-band decomposition module 1010. Similar to the subband decomposition module 420 described in fig. 4, the subband decomposition module 1010 may include at least two band pass filters, each of which may perform band pass filtering on the electrical signal generated by the acoustoelectric transducer 410 to generate at least two subband noise signals. Each band pass filter may also include a digital signal processor that may implement the functionality of a sub-band noise suppression module (e.g., sub-band noise suppression module 700 or 900 as described in fig. 7 and 9). For example only, the digital signal processor may perform phase modulation and/or amplitude modulation on the sub-band noise signals to generate corresponding sub-band noise modification signals. In this way, the sub-band noise suppression module can be omitted from the noise reduction apparatus, which can simplify the structure of the noise reduction apparatus.

It should be noted that the above description of sub-band noise sensor 220C is intended to be illustrative, and not to limit the scope of the present application. Many alternatives, modifications, and variations will be apparent to those skilled in the art. The features, structures, methods, and other features of the exemplary embodiments described herein may be combined in various ways to obtain additional and/or alternative exemplary embodiments. For example, sub-band noise sensor 220C may include one or more additional components. Additionally or alternatively, one or more components of sub-band noise sensor 220C described above may be omitted. In some embodiments, the subband decomposition module 1010 may generate the subband noise corrected signal without performing amplitude modulation.

FIG. 11 is a schematic diagram of an exemplary noise reduction system 1100 shown in accordance with some embodiments of the present application. The noise reduction system 1100 may be an exemplary embodiment of the noise reduction system 100A as described in fig. 1A. As shown in FIG. 11, the noise reduction system 1100 may include an ambient noise reducer 120A, a residual noise reducer 150A, a synthesis module 1120, and an output module 170. The ambient noise reducer 120A and the residual noise reducer 150A may be exemplary embodiments of the ambient noise reducer 120 and the residual noise reducer 150, respectively.

The ambient noise reducer 120A may be configured to suppress the ambient noise 110 using a sub-band noise reduction technique. As shown in FIG. 11, the ambient noise reducer 120A may have a similar structure as the noise reducer 200 described in FIG. 2. The ambient noise reducer 120A may include a sub-band noise sensor 220, at least two sub-band noise suppression modules 230, and a synthesis module 240. The sub-band noise sensor 220 may detect the ambient noise 110 and generate at least two sub-band ambient noise signals (e.g., sub-band ambient noise signals a1 through Am). The sub-band ambient noise signal generated based on the ambient noise 110 may be similar to the sub-band noise signal generated based on the noise 210 as described in fig. 2.

The sub-band noise suppression module 230 may generate at least two sub-band ambient noise modification signals (e.g., sub-band ambient noise modification signals a1 'through Am'), each for suppressing one sub-band ambient noise signal. The sub-band ambient noise modification signal used to suppress the sub-band ambient noise signal may be similar to the sub-band noise modification signal used to suppress the sub-band noise signal, as described in fig. 2. The synthesis module 240 may combine the sub-band ambient noise correction signals to generate the ambient noise correction signal 130 and send the ambient noise correction signal 130 to the synthesis module 1120.

The residual noise reducer 150A may be configured to suppress the residual noise 140 using a full-band noise reduction technique. The residual noise reduction device 150A may include a residual noise sound sensor 1130 and a residual noise reduction module 1110. The residual noise sensor 1130 may be configured to detect the residual noise 140 and generate a residual noise signal in response to the detected residual noise 140. For example, residual noise sensor 1130 may include an acoustoelectric transducer that may generate a residual noise signal having the same (or substantially the same) frequency band as residual noise 140. In some embodiments, the residual noise sensor 1130 may be mounted near or within the output module 170. For example, the residual noise sensor 1130 may be mounted within the output module 170 near an acoustic channel from which the audio signal for suppressing the ambient noise 110 is generated. The residual noise reduction module 1110 may be configured to receive the residual noise signal from the residual noise sensor 1130 and generate the residual noise correction signal 160 for suppressing the residual noise 140. The residual noise correction signal 160 may be sent from the residual noise reduction module 1110 to the synthesis module 1120.

In some alternative embodiments, the residual noise reducer 150A may utilize sub-band noise reduction techniques to suppress the residual noise 140. For example only, the residual noise reducer 150A may have a similar structure to the noise reducer 200 described in FIG. 2. The residual noise sensor 1130 and the residual noise reduction module 1110 may have similar functions as the sub-band noise sensor 220 and the sub-band noise suppression module 230, respectively. The residual noise signal generated by the residual noise sensor 1130 may include at least two sub-band residual noise signals, each of which may have a narrower frequency band than the residual noise 140. The residual noise correction signal 160 generated by the residual noise reduction module 1110 may comprise at least two subband residual noise correction signals for suppressing the subband residual noise signal or a synthesized signal of the subband residual noise correction signals.

The synthesis module 1120 may be configured to combine the ambient noise correction signal 130 and the residual noise correction signal 160 to generate a synthesized signal, which may be sent to the output module 170 for output. In some embodiments, the synthesized signal generated by the synthesis module 1120 may be a digital signal, and the output module 170 may convert the synthesized signal into an audio signal for output.

FIG. 12 is a schematic diagram of an exemplary noise reduction system 1200 shown in accordance with some embodiments of the present application. Noise reduction system 1200 may be an exemplary embodiment of noise reduction system 100B as described in fig. 1B. Noise reduction system 1200 may be similar to noise reduction system 1100 described in FIG. 11, except for certain components or features. In contrast to noise reduction system 1100, noise reduction system 1200 may also include a digital-to-analog converter 1210, a digital-to-analog converter 1230, and an output module 180. The ambient noise correction signal 130 generated by the ambient noise reducer 120A and the residual noise correction signal 160 generated by the residual noise reducer 150A may be processed and output separately without being synthesized.

In some embodiments, the ambient noise correction signal 130 and the residual noise correction signal 160 may be digital signals. The digital-to-analog converters 1210 and 1230 may be configured to convert the ambient noise correction signal 130 and the residual noise correction signal 160 into analog signals 1220 and 1240, respectively. The analog signal 1220 may further be sent from the digital-to-analog converter 1210 to the output module 170 for output. Analog signals 1240 may also be sent from digital-to-analog converter 1230 to output module 180 for output.

FIG. 13 is a schematic diagram of an exemplary noise reduction system 1300 shown in accordance with some embodiments of the present application. The noise reduction system 1300 may be similar to the noise reduction system 1100 described in FIG. 11, except for certain components or features. As shown in fig. 13, the noise reduction system 1300 may include an ambient noise reducer 120A, a residual noise reducer 150B, and an output module 170. The ambient noise modification signal 130 generated by the ambient noise reducer 120A may be output by the output module 170.

The residual noise reduction device 150B may include a residual noise sound sensor 1130 and a feedback module 1310. The feedback module 1310 may be configured to adjust the sub-band noise suppression module 230 according to the residual noise 140 to suppress the residual noise 140. For example, the adjustment unit may send instructions to one or more of subband noise suppression modules 230 to adjust one or more parameters of subband noise suppression modules 230. By way of example only, as described in this application (e.g., fig. 7-9 and related description), subband noise suppression module 230 may include a phase modulator (e.g., phase modulator 710) and/or an amplitude modulator (e.g., amplitude modulator 720). Feedback module 1310 may send instructions to subband noise suppression module 230 to adjust a time delay (e.g., Δ T) of a phase modulator and/or an amplitude attenuation coefficient (e.g., a) of an amplitude modulator_t) So that the ambient noise 110 is suppressed by the ambient noise modification signal 130 and no or substantially no residual noise is generated. In this way, the sub-band noise suppression module 230 may be automatically adjusted according to the residual noise 140, which improves the accuracy and stability of the noise reduction system 1300.

It should be noted that the above description of fig. 11-13 is provided for illustrative purposes only and is not intended to limit the scope of the present application. Various changes and modifications will occur to those skilled in the art based on the description herein. However, such changes and modifications do not depart from the scope of the present application. A noise reduction system (e.g., any of noise reduction systems 1100, 1200, and 1300) may include one or more additional components and/or may omit one or more components of the noise reduction system. For example only, digital-to-analog converter 1210 may be omitted from noise reduction system 1200 or integrated into output module 170. For another example, in noise reduction system 1200, synthesis module 240 may be omitted and the sub-band noise environment modification signal may be sent to at least two output units of output module 170 for output.

FIG. 14 is a schematic diagram of an exemplary residual noise reducer 150C, shown in accordance with some embodiments of the present application. The residual noise reducer 150C may be an exemplary embodiment of the residual noise reducer 150 that may be used to suppress the residual noise 140 using sub-band noise reduction techniques.

As shown in FIG. 14, the residual noise reducer 150C may have a similar structure to the noise reducer 200 described in FIG. 2. The residual noise reduction device 150C may include a sub-band noise sensor 220, at least two sub-band noise suppression modules 230, and a synthesis module 240. The sub-band noise sensor 220 may be mounted near the output module 170 to detect the residual noise 140 and generate at least two sub-band residual noise signals (e.g., sub-band residual noise signals R1 through Rk). The subband noise suppression block 230 may generate at least two subband residual noise modifying signals (e.g., subband residual noise modifying signals R '1 to R' k), one of which is used to suppress one subband residual noise signal. The synthesis module 240 may synthesize the subband residual noise correction signals to generate the residual noise correction signal 160. The residual noise correction signal 160 may further be sent to an output module 170 for output.

In some embodiments, the subband noise suppression modules 230-i may include a phase modulator (e.g., a phase inverter) configured to perform phase inversion on the corresponding subband residual noise signals Ri. Since the sub-band noise sensor 220 for detecting the residual noise 140 is installed near the output module 170, the sub-band noise suppression module 230-i may not perform phase compensation and/or amplitude modulation on the sub-band residual noise signal Ri while generating the corresponding sub-band residual noise correction signal Ri'.

FIG. 15 is a schematic diagram illustrating an example noise reduction system 1500 according to some embodiments of the present application. Noise reduction system 1500 may be similar to noise reduction system 1100 depicted in FIG. 11, except that noise reduction system 1500 applies analog signal processing techniques to suppress noise. As shown in fig. 15, the noise reduction system 1500 may include an ambient noise reducer 120B, a residual noise reducer 150D, a synthesis module 1505, and an output module 170.

The ambient noise reduction device 120B may include a sub-band noise sensor (not shown in FIG. 15), at least two analog signal processing components 1501 (e.g., analog signal processing components 1501-1 to 1501-m), and a synthesis module 1504. The sub-band noise sensor of the ambient noise reducer 120B may detect the ambient noise 110 and generate sub-band ambient noise signals (e.g., sub-band ambient noise signals N1 through Nm). The sub-band ambient noise signal generated by the sub-band noise sensor of the ambient noise reduction device 120B may be an analog signal.

The analog signal processing component 1501 may have a similar function to the sub-band noise suppression module 230 of the ambient noise reduction apparatus 120A described in fig. 11. For example, the analog signal processing component 1501 may receive the sub-band ambient noise signal and generate at least two sub-band ambient noise correction signals (e.g., sub-band ambient noise correction signals N1 'through Nm'). The sub-band ambient noise correction signal generated by the analog signal processing component 1501 may be an analog signal. The sub-band ambient noise correction signals may be combined by the synthesis module 1504 into an ambient noise correction signal 130', which may be an analog signal for suppressing ambient noise.

In some embodiments, analog signal processing components 1501-i may include one or more first analog circuit components for performing phase modulation on sub-band ambient noise signal Ni. The phase modulation performed by the first analog circuit component may be similar to the phase modulation performed by a phase modulator (e.g., phase modulator 710) described elsewhere herein (e.g., fig. 7-9 and related description). For example, the first analog circuit component may include an amplifier (e.g., an inverting amplifier) for performing phase inversion on the sub-band ambient noise signal Ni. Additionally or alternatively, the first analog circuit component may include an analog delay line (e.g., inductor-capacitor (LC) circuit delay line, active analog delay line) to compensate for phase offset on the sub-band ambient noise signal Ni.

The residual noise reduction device 150D may include a residual noise sensor 1503 and an analog signal processing component 1502. Residual noise sensor 1503 may detect residual noise 140 and generate a residual noise signal in the form of an analog signal. The analog signal processing component 1502 may be configured to generate a residual noise correction signal 160', which may be an analog signal for suppressing the residual noise 140. The synthesis module 1505 may be configured to combine the ambient noise correction signal 130 'and the residual noise correction signal 160' to generate a combined analog signal. The combined analog signal may be output by output module 170.

By using analog signal processing components, noise reduction system 1500 may suppress ambient noise and residual noise 140 without a sampling module (e.g., sampling module 620), digital-to-analog converters (e.g., digital-to-analog converters 1210 and 1230), analog-to-digital converters, etc., thereby simplifying noise reduction system 1500 and improving the operating efficiency of noise reduction system 1500.

Having thus described the basic concepts, it will be apparent to those of ordinary skill in the art having read this application that the foregoing disclosure is to be construed as illustrative only and is not limiting of the application. Various modifications, improvements and adaptations of the present application may occur to those skilled in the art, although they are not explicitly described herein. Such modifications, improvements and adaptations are proposed in the present application and thus fall within the spirit and scope of the exemplary embodiments of the present application.

Also, this application uses specific language to describe embodiments of the application. For example, "one embodiment," "an embodiment," and/or "some embodiments" means that a particular feature, structure, or characteristic described in connection with at least one embodiment of the application. Therefore, it is emphasized and should be appreciated that two or more references to "an embodiment" or "one embodiment" or "an alternative embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, certain features, structures, or characteristics of one or more embodiments of the application may be combined as appropriate.

Moreover, those of ordinary skill in the art will understand that aspects of the present application may be illustrated and described in terms of several patentable species or situations, including any new and useful combination of processes, machines, articles, or materials, or any new and useful improvement thereof. Accordingly, various aspects of the present application may be embodied entirely in hardware, entirely in software (including firmware, resident software, micro-code, etc.) or in a combination of hardware and software. The above hardware or software may be referred to as a "unit", "module", or "system". Furthermore, aspects of the present application may be represented as a computer product, including computer readable program code, embodied in one or more computer readable media.

A computer readable signal medium may comprise a propagated data signal with computer program code embodied therewith, for example, on baseband or as part of a carrier wave. Such a propagated signal may take any of a variety of forms, including electro-magnetic, optical, and the like, or any suitable combination. A computer readable signal medium may be any computer readable medium that is not a computer readable storage medium and that can communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device. Program code on a computer readable signal medium may be propagated over any suitable medium, including radio, cable, fiber optic cable, RF, etc., or any combination of the preceding.

Computer program code required for the operation of various portions of the present application may be written in any one or more of a variety of programming languages, including a subject oriented programming language such as Java, Scala, Smalltalk, Eiffel, JADE, Emerald, C + +, C #, VB.NET, Python, and the like, a conventional programming language such as C, Visual Basic, Fortran 2003, Perl, COBOL 2002, PHP, ABAP, a dynamic programming language such as Python, Ruby, and Groovy, or other programming languages. The program code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user's computer through any network format, such as a Local Area Network (LAN) or a Wide Area Network (WAN), or the connection may be made to an external computer (for example, through the Internet), or in a cloud computing environment, or as a service, such as a software as a service (SaaS).

Additionally, the order in which elements and sequences of the processes described herein are processed, the use of alphanumeric characters, or the use of other designations, is not intended to limit the order of the processes and methods described herein, unless explicitly claimed. While various presently contemplated embodiments of the invention have been discussed in the foregoing disclosure by way of example, it is to be understood that such detail is solely for that purpose and that the appended claims are not limited to the disclosed embodiments, but, on the contrary, are intended to cover all modifications and equivalent arrangements that are within the spirit and scope of the embodiments herein. For example, although the system components described above may be implemented by hardware devices, they may also be implemented by software-only solutions, such as installing the described system on an existing server or mobile device.

Similarly, it should be noted that in the preceding description of embodiments of the present application, various features are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the embodiments. This method of application, however, is not to be interpreted as reflecting an intention that the claimed subject matter to be scanned requires more features than are expressly recited in each claim. Indeed, the embodiments may be characterized as having less than all of the features of a single embodiment disclosed above.