Earphone with system for reducing ambient noise
阅读说明:本技术 具有降低环境噪声系统的耳机 (Earphone with system for reducing ambient noise ) 是由 马斯·德尔霍尔姆 艾伦·迈伊格伦·冯·比洛 于 2018-12-07 设计创作,主要内容包括:一种耳机(1;101),适于发送输出音频信号(Tx),并包括语音麦克风(12)和至少一个环境麦克风(21)。耳机包括环境降噪块(ANR),该模块适于降低输出音频信号(Tx)中的环境噪声电平。环境降噪块(ANR)包括测量语音麦克风信号(X)和环境麦克风信号(Y)的电平,以估计语音麦克风信号(X)和环境麦克风信号(Y)之间的特性恒定电平降,这是耳机用户讲话的特征。当电平差大于特性恒定电平降(CLD)时,时变滤波器会使语音麦克风信号(X)通过,且如果电平差小于特性恒定电平降,则时变滤波器会使语音麦克风信号(X)衰减。(A headset (1; 101) is adapted to transmit an output audio signal (Tx) and comprises a speech microphone (12) and at least one ambient microphone (21). The headphone comprises an ambient noise reduction block (ANR) adapted to reduce the ambient noise level in the output audio signal (Tx). The ambient noise reduction block (ANR) includes measuring the levels of the speech microphone signal (X) and the ambient microphone signal (Y) to estimate a characteristic constant level drop between the speech microphone signal (X) and the ambient microphone signal (Y), which is characteristic of the headset user speaking. The time-varying filter passes the voice microphone signal (X) when the level difference is greater than a characteristic Constant Level Drop (CLD), and attenuates the voice microphone signal (X) if the level difference is less than the characteristic constant level drop.)
1. A headset (1; 101) adapted to transmit an output audio signal (Tx), the headset (1) comprising:
a) a speech microphone (12) for generating a speech microphone signal (X),
b) at least one ambient microphone (21) generating an ambient microphone signal (Y), wherein the speech microphone (12) is arranged at a first distance (D1) from a user's mouth and the ambient microphone (21) is arranged at a second distance (D2) from the user's mouth when the headset (1) is worn by a user, wherein the first distance (D1) is smaller than the second distance (D2),
c) an ambient noise reduction block (ANR) adapted to reduce a level of ambient noise in the output audio signal (Tx), wherein the ambient noise reduction block (ANR) comprises the steps of:
I. detecting that a headset user (23) is speaking,
measuring the levels of the speech microphone signal (X) and the ambient microphone signal (Y) to estimate a characteristic constant level drop between the speech microphone signal (X) and the ambient microphone signal (Y), which is characteristic of the headset user speaking,
constructing a time-varying filter for removing noise,
detecting a level difference between the speech microphone signal (X) and the ambient microphone signal (Y),
v. comparing a level difference between the speech microphone signal (X) and the ambient microphone signal (Y) with the characteristic constant level drop,
when the level difference is greater than the characteristic Constant Level Drop (CLD), the time-varying filter passes the speech microphone signal (X),
-if said level difference is smaller than said characteristic constant level drop, said time-varying filter will attenuate said speech microphone signal (X).
2. The headset (1; 101) according to claim 1, wherein the steps i-vii.
3. The headset (1; 101) according to claim 2, wherein the step i-the step vii.
4. A headset (1; 101) according to claim 3, wherein the step i-the step vii.
5. A headset (1; 101) according to any of the preceding claims, wherein the speech microphone signal (X) and the ambient microphone signal (Y) are divided into a plurality of frequency bands.
6. A headset (1; 101) according to claim 5, wherein a fast Fourier transform algorithm transforms the speech microphone signal (X) and the ambient microphone signal (Y) into the frequency domain before reaching the ambient noise reduction block (ANR), and wherein an inverse Fourier transform algorithm transforms the Tx signal into the time domain.
7. A headset (1; 101) according to any of the preceding claims, wherein the at least one ambient microphone (21, 22) is an active noise cancellation microphone.
8. The headset (101) of any one of the preceding claims, wherein the headset (1) comprises a microphone arm (23), wherein the speech microphone (12) is located at a free end of the microphone arm (23).
9. The headset (101) of claim 1 comprising: a right ambient microphone (3) producing a right ambient microphone signal (YR); and a left ambient microphone (4) generating a left ambient microphone signal (YL); wherein the right ambient microphone (3) and the left ambient microphone (4) are both arranged at the second distance (D2) from the user's mouth when the headset (1) is worn by a user, wherein the ambient microphone signal (Y) received by the ambient noise reduction block (ANR) is the difference between one of a first and a second ambient microphone signal (YR) and an attenuated version (YL') of the other of the first and the second ambient microphone signal (YR, YL).
10. A headset (1) according to claim 6, wherein the attenuated version (YL') of the first or second ambient microphone signal is attenuated by between 3dB and 9dB, preferably by about 6 dB.
11. A headset (1) according to claim 9 or 10, wherein the right ambient microphone (3) and the left ambient microphone (4) are symmetrically arranged on each side of the sagittal plane when the headset (1) is worn.
12. A headset (1) according to any of the claims 6-8, wherein the headset comprises a first headset (2; 28) and a second headset (3; 28), wherein a right ambient microphone (21) is located at the first headset (2; 28) and a left ambient microphone (21) is located at the second headset (3; 28).
Technical Field
The invention relates to a headset adapted to transmit an output audio signal, the headset comprising a speech microphone, generating a speech microphone signal; at least one ambient microphone generating an ambient microphone signal; wherein the voice microphone is arranged a first distance from the user's mouth and the ambient microphone is arranged a second distance from the user's mouth when the headset is worn by the user, wherein the first distance is smaller than the second distance.
Background
Headsets of the type described above may be equipped with headphones or earpieces and used for listening to audio (e.g., music) and two-way communication. It may be wired and plugged into a smart phone or computer, or wireless and equipped with a transceiver, such as a bluetooth transceiver. Other types of headphones include two headphones, a headband that connects the headphones and a microphone arm by which the microphone can be placed close to the user's mouth during use. It is a great advantage to be able to place the microphone close to the mouth, since a better signal-to-noise ratio is obtained. This is why this type of headset is the most widely used headset for telecommunications in call centres and offices. When a user uses such a headset for two-way communication, ambient noise (e.g., speech from other office workers in the office) may become a problem. First, noise may be transmitted to the other end together with the sound of the user of the headset, which may cause interference. Secondly, communications (which may be confidential) in the office may reach the party at the other end of the communication line, which is of course undesirable. Accordingly, there is a need to provide an improved ambient noise reduction system for headphones.
Disclosure of Invention
The headphone according to the preliminary part comprises an ambient noise reduction block adapted to reduce an ambient noise level in the output audio signal, wherein the ambient noise reduction block comprises the steps of:
detecting that a user of the headset is speaking,
measuring the levels of the speech microphone signal and the ambient microphone signal to estimate a characteristic constant level drop between the speech microphone signal and the ambient microphone signal, which is characteristic of the speech of the user of the headset,
constructing a time-varying filter to remove noise,
IV, detecting the level difference between the voice microphone signal and the environment microphone signal,
v, comparing the level difference between the voice microphone signal and the ambient microphone signal with the characteristic constant level drop,
when the level difference is larger than the characteristic constant level drop, the time-varying filter will make the voice microphone signal pass through,
and VII, if the level difference is smaller than the characteristic constant level drop, the time-varying filter can attenuate the signal of the voice microphone.
With such a headset, the ambient noise level in the signal transmitted from the headset can be effectively eliminated. The steps listed above are carried out continuously, which means many times per second, in practice up to 250 times per second. It is important that the system has continuous adaptability, as the exact position of the microphone relative to the user's mouth varies constantly: first, due to anatomical differences when different users wear the headset; secondly, due to the freedom of positioning of the headset on the respective user; and thirdly, due to the user's movements, e.g. turning the head, the exact position of the mouth with respect to the microphone geometry is changed and/or the geometry of the microphone system itself is changed.
According to an embodiment, steps l.
According to an embodiment, steps l.
According to an embodiment, steps l.
According to an embodiment, steps l.
According to an embodiment, the speech microphone signal and the ambient microphone signal are divided into a plurality of frequency bands, for example 65 frequency bands.
According to an embodiment, the fast fourier transform algorithm transforms the speech microphone signal and the ambient microphone signal into the frequency domain before reaching the ambient noise reduction block, and wherein the inverse fourier transform algorithm transforms the Tx signal into the time domain. Other filter banks may be used.
The at least one ambient microphone may be an active noise cancellation microphone.
The headset may include a microphone arm, wherein the voice microphone is located at a free end of the microphone arm.
According to an embodiment, the headset comprises a right ambient microphone generating a right ambient microphone signal; and a left ambient microphone that generates a left ambient microphone signal; wherein, when the user wears the headset, both the right ambient microphone and the left ambient microphone are disposed at a second distance from the user's mouth, wherein the ambient microphone signal received by the ambient noise reduction block is the difference between one of the first and second ambient microphone signals and an attenuated version of the other of the first and second ambient microphone signals.
The attenuated version of the first or second ambient microphone signal may be attenuated by between 3dB and 9dB, preferably by about 6 dB.
According to an embodiment, the right and left ambient microphones are symmetrically arranged on each side of the sagittal plane when the headset is worn.
According to an embodiment, the headset comprises a first headset/earpiece and a second headset/earpiece, wherein the right ambient microphone is located at the first headset/earpiece and the left ambient microphone is located at the second headset/earpiece.
According to an embodiment, the headset comprises a first and a second ear plug and a connecting portion connecting the first and the second ear plug, the connecting portion comprising a neck portion adapted to be worn on the neck between a first neck end and a second neck end, and wherein a first cable portion extends between the first neck end and the first ear plug and a second cable portion extends between the second neck end and the second ear plug, wherein a microphone case is arranged on the first cable portion between the first neck end and the first ear plug such that a first cable element of the first cable portion extends between the first neck end and the microphone case and a second cable element of the cable portion extends between the microphone case and the first ear plug, and wherein the connecting portion is adapted such that the first neckband end points in a first direction when the headset is worn, and wherein the first cable element has a first cable element length and a first cable element flexibility, and the second cable element having a second cable element length and a second cable element flexibility, characterized in that the first ear plug, the first direction, the first cable element length, the first cable element flexibility, the second cable element length, the second cable element flexibility are adapted such that the microphone case, when worn, will be located at a first distance of the mouth of the user, the first distance being smaller than 8 centimeters.
The voice microphone may be an omni-directional microphone.
Drawings
The invention is explained in detail below with reference to the drawings showing preferred embodiments of the invention, in which
Figure 1 is a perspective view of a headset according to a first embodiment,
figure 2 is a perspective view of a headset worn by a user,
figure 3 is a perspective view of another angle of the headset,
figure 4 is a front view of the headset in the "not in use" position,
figure 5 is a schematic view of the microphone system of the headset shown in figures 1-4,
figure 6 is a schematic view of the ambient noise system of the headset shown in figures 1-4,
figure 7 is a perspective view of a headset according to a second embodiment,
fig. 8 is a schematic diagram of a microphone system of the headset shown in fig. 7, and fig. 9 is a table showing differences between the microphone systems shown in fig. 5 and 8.
Detailed Description
Fig. 1 is a perspective view of a headset. The earpiece is an ear-bud wireless earpiece, meaning that it is fitted with a small ear bud that can be inserted into the ear of the user. It thus comprises a
The rechargeable battery is disposed in the body portion 18. The electronic device including the bluetooth transceiver is mainly arranged in the right arm and the left arm. An
Fig. 2 is a perspective view of the
Fig. 3 is a perspective view of the headset from another angle. The total length L5 of the neck 5 is 393 mm. The length of the first cable element 81 is 83mm and the length L82 of the second cable element 82 is 100 mm. The length L10 of the
Fig. 4 is a front view of the headset in an "unused" or "relaxed" position. The maximum distance D4 between the neck curvatures 16, 17 is 128 mm. The angle VI between the sagittal plane PS and the pointing direction is about 20 degrees. The first and
Fig. 7 is a perspective view of the
Fig. 8 is a schematic diagram of the microphone system of the
The difference between the speech microphone signal XK and the ambient microphone signal YK serves as an indication that the signals in the frequency bin k are primarily user speech.
Fig. 5 is a schematic view of a microphone system of the headset shown in fig. 1-4. As previously mentioned, the headset comprises a
Another attenuation, e.g. 3dB or 9dB, may be used. However, it has been shown that 6dB provides a good compromise between obtaining a high level difference or signal level drop from the speech microphone signal to the ambient microphone signal and also prevents the risk of creating a return-to-zero plane.
Fig. 6 is a schematic view of an ambient noise reduction system ANS of the
the microphone is adapted to:
a running estimate of the expected decrease in amplitude of the sound pressure level SPL when the user speaks.
Whether and how much to adjust is estimated, depending on:
1) the instantaneous sound pressure level at the voice microphone is above some set level.
2) The instantaneous sound pressure level at the voice microphone is higher than the average noise measured at the voice microphone by some set level.
3) The short-term average of the coherence between the speech microphone signal X and the ambient microphone signal Y is higher than the long-term optimum coherence between the microphone signals within the tolerance range.
And noise reduction gain calculation:
an NR (noise reduction) gain for each frequency band is calculated based on the estimation. The measurement bands which exhibit an amplitude difference between the
Noise reduction enhancement and smoothing
Enhancing the ability to reduce noise in frequency bands that have limited impact on the headset user's speech.
And according to the certainty that the user of the earphone does not speak, the noise reduction effect of all frequency bands is improved.
And according to the certainty that the earphone user does not speak, performing smoothing across frequency bands.
NR limiter
The amount of noise reduction allowed for each band is calculated from the difference between the stationary noise and the average speech level of the user of the headset.
Fig. 9 is a table showing the differences between the microphone systems shown in fig. 5 and 8 in two different situations. The second row shows the 2-microphone solution shown in fig. 8, which is the relationship between the ambient microphone signal Y and the speech microphone signal X in case the
Reference numbers:
pointing direction of A1 first neck end
ANS environmental noise reduction system
ANR environmental noise reduction block
D1 first distance (between voice microphone and mouth)
D2 second distance (between the ambient microphone and the mouth)
D3 third distance (between ear canal and microphone box)
Maximum distance between neck curvatures D4
Distance between the D5 speech microphone and the first ambient microphone
Angle between VIA1 and PS
PS sagittal plane
L5 neck Length
L10 microphone case length
L81 first cable element length
L82 second Cable element Length
Flexibility of F81 first cable section
Flexibility of F82 second cable section
X-voice microphone signal
Y environment microphone signal
YR Right Environment microphone Signal
YL left-side Environment microphone Signal
1 earphone
2 first earplug
3 second earplug
4 connecting part
5 neck part
6 first neck end
7 second neck end
8 first cable part
9 second cable part
10 microphone box
11 Sound outlet
12 voice microphone
13 control button
14-ear glue
15 earrings
16 first neck curvature
17 second neck curvature
18 main body part of neck
19 right arm of neck
20 left arm of neck
21 right environment microphone
22 left environment microphone
23 microphone arm
24 head band
25 electric cable
26 users
27 noise maker
28 earphone
29 microphone opening
81 first cable element
82 a second cable member.
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