阅读说明：本技术 一种扬声器阵列的声场控制方法 (Sound field control method of loudspeaker array ) 是由 闫峻 顾舜 张屹 于 2021-08-26 设计创作，主要内容包括：本发明涉及一种扬声器阵列声场控制方法,通过本发明的声场控制方法,在不需要调节扬声器单元角度的情况下,可以根据扬声器阵列覆盖角的需要,结合空间重采样法和CBT阵列理论改变预设扬声器阵列的加权系数,实现高于截止频率F和低于截止频率F的在一个扬声器阵列上实现恒定束宽的分配控制,有效的抑制声场的旁瓣,适用于各种建声环境,同时还能达到改变其声波传送方向目标的效果。(The invention relates to a loudspeaker array sound field control method, through the sound field control method of the invention, under the condition that does not need to adjust the angle of a loudspeaker unit, can combine the space resampling method and CBT array theory to change the weighting coefficient of the preset loudspeaker array according to the requirement of the loudspeaker array coverage angle, realize the distribution control of the constant beam width on a loudspeaker array higher than the cut-off frequency F and lower than the cut-off frequency F, the sidelobe of the sound field is restrained effectively, suitable for various sound-building environments, can also reach the effect of changing its sound wave transmission direction goal at the same time.)

1. A sound field control method of a loudspeaker array is characterized by comprising an upper computer and the loudspeaker array consisting of M loudspeaker array elements, wherein each loudspeaker array element is provided with a time delay, and the sound field control method comprises the following steps:

step 1, setting a loudspeaker array, and presetting a coverage angle theta of the loudspeaker array_-6db；

Step 2, according to the coverage angle theta of the loudspeaker array_-6dbObtaining a cut-off frequency F;

step 3, performing constant beam width control on the frequency section of the audio signal, which is smaller than the cut-off frequency F, by adopting a space resampling method; performing constant beam width control on a frequency segment of which the audio signal is greater than or equal to a cut-off frequency F by adopting a CBT array theory;

and 4, carrying out frequency division processing on the audio signals input into the loudspeaker array, and respectively transmitting the high-frequency signals and the low-frequency signals to a high-frequency unit and a low-frequency unit of the loudspeaker array element for output and play.

2. The sound field control method of a speaker array as claimed in claim 1, wherein the cut-off frequency in step 2 is:

where H is the equivalent overall length of the loudspeaker array based on CBT theory.

3. The method as claimed in claim 1, wherein the step 3 of performing constant beamwidth control on the frequency segment smaller than the cut-off frequency F by using the spatial resampling method specifically includes:

S31A, dividing frequency segment into j frequency bands, and determining reference frequency f by using Chebyshev weighting method₀M loudspeaker elements with a weighting factor w₀(m)；

S32A, calculating other frequency bands f by a space resampling method_jWeighting coefficient w of the m-th loudspeaker array element_jThe formula (m) is as follows:

m＝1,2,...,M；

S33A. according to the weighting coefficient w_j(m) calculating the expected response of each loudspeaker array element filter by adopting a frequency response formula;

in the formula, w (f)_j) Is a design index of the filter;

S34A, solving filter coefficients corresponding to loudspeaker array elements by using a Least Square (LS) algorithm according to expected responses of the filters;

S35A, each loudspeaker array element outputs a beam with constant beam width according to the corresponding filter coefficient;

the step 3 of performing constant beam width control on the frequency segment greater than or equal to the cutoff frequency F by using the CBT array theory specifically includes:

S31B, adding delay factors of the delayers to each loudspeaker array element to enable the phase of the loudspeaker array to form an arc array with the radius r, wherein the delay factor tau meets the following requirements:

Φ＝(1-cos(θ_i))r

τ＝Φ/c

wherein c is the sound velocity of sound in air;

S32B, according to the CBT theory, the radial sound pressure distribution of the sound pressure of the frequency section, larger than or equal to the cut-off frequency F, of the arc array in the far and near fields meets the following requirements:

where ρ (θ) is a radial sound pressure distribution, P_v(cos θ) is the Legendre function, and v is the order of the Legendre function; theta is the elevation angle of the corresponding coordinate of the position where the loudspeaker array element is located; theta₀Is P_v(cos θ) minimum zero;

S33B, simplifying calculation of a Legendre function, deducing a third-order polynomial to approximately express the weighting coefficient of each loudspeaker array element as follows:

in the formula (I), the compound is shown in the specification,

and S34B, outputting the beam with constant beam width by each loudspeaker array element according to the weighting coefficient.

Technical Field

The invention relates to the technical field of sound direction adjustment, in particular to a sound field control method of a loudspeaker array.

Background

The loudspeaker array is an array loudspeaker system which is formed by arranging loudspeakers or transducers as array elements according to a certain geometrical structure. And combining different geometric array types to process the electric signals applied by the loudspeaker array, wherein the electric signals comprise amplitude, phase, frequency and other electric appliance characteristic quantities, and different space sound field distributions can be obtained.

Most of the currently used loudspeaker arrays are loudspeaker linear arrays, and a plurality of defects exist in the aspect of sound field form control capability. Especially, the current speaker array intelligence performs directivity control and constant beam width control in a specific direction, and cannot generate a sound field with a constant beam width in the entire operating frequency band, and the side lobes of the speaker array cannot be effectively suppressed. For example, when the frequency of the signal is different, the corresponding beam pattern is also different, and therefore, waveform distortion (i.e., side lobe) is generated when the transmission signal bandwidth is used, and the waveform distortion is more serious the larger the signal bandwidth is.

Disclosure of Invention

The technical problem to be solved by the invention is to provide a sound field control method of a loudspeaker array, which is used for inhibiting sound field side lobes and controlling the directivity of the loudspeaker array.

The technical scheme adopted by the invention is that the sound field control method of the loudspeaker array comprises an upper computer and the loudspeaker array consisting of M loudspeaker array elements, wherein each loudspeaker array element is provided with a time delayer, and the sound field control method comprises the following steps:

step 1, setting a loudspeaker array, and presetting a coverage angle theta of the loudspeaker array_-6db；

Step 2, according to the loudspeaker array and the coverage angle theta_-6dbObtaining a cut-off frequency F;

step 3, performing constant beam width control on the frequency section of the audio signal, which is smaller than the cut-off frequency F, by adopting a space resampling method; performing constant beam width control on a frequency segment of which the audio signal is greater than or equal to a cut-off frequency F by adopting a CBT array theory;

step 4, carrying out frequency division processing on the audio signals input into the loudspeaker array, and respectively transmitting the high-frequency signals and the low-frequency signals to a high-frequency unit and a low-frequency unit of the loudspeaker array element for output and play

The invention has the beneficial effects that: by the sound field control method, under the condition that the angle of the loudspeaker unit does not need to be adjusted, the weighting coefficient of the preset loudspeaker array can be changed according to the requirement of the coverage angle of the loudspeaker array by combining a space resampling method and a CBT array theory, the distribution control of constant beam width on one loudspeaker array higher than a cut-off frequency F and lower than the cut-off frequency F is realized, the side lobe of a sound field is effectively restrained, the sound field control method is suitable for various sound construction environments, and the effect of changing the sound wave transmission direction target of the sound field can be achieved.

Preferably, the cut-off frequency in step 2 is:

where H is the equivalent overall length of the loudspeaker array based on CBT theory.

Preferably, the performing of the constant beam width control on the frequency segment smaller than the cut-off frequency F by using the spatial resampling method in the step 3 specifically includes:

S31A, dividing frequency segment into j frequency bands, and determining reference frequency f by using Chebyshev weighting method₀M loudspeaker elements with a weighting factor w₀(m)；

S32A, calculating other frequency bands f by a space resampling method_jWeighting coefficient w of the m-th loudspeaker array element_jThe formula (m) is as follows:

S33A. according to the weighting coefficient w_j(m) calculating the expected response of each loudspeaker array element filter by adopting a frequency response formula;

in the formula, w (f)_j) Is a design index of the filter;

S34A, solving filter coefficients corresponding to loudspeaker array elements by using a Least Square (LS) algorithm according to expected responses of the filters;

S35A, each loudspeaker array element outputs a beam with constant beam width according to the corresponding filter coefficient;

the step 3 of performing constant beam width control on the frequency segment greater than or equal to the cutoff frequency F by using the CBT array theory specifically includes:

S31B, adding delay factors of the delayers to each loudspeaker array element to enable the phase of the loudspeaker array to form an arc array with the radius r, wherein the delay factor tau meets the following requirements:

Φ＝(1-cos(θ_i))r

τ＝Φ/c

wherein c is the sound velocity of sound in air;

S32B, according to the CBT theory, the radial sound pressure distribution of the sound pressure of the frequency section, larger than or equal to the cut-off frequency F, of the arc array in the far and near fields meets the following requirements:

where ρ (θ) is a radial sound pressure distribution, P_v(cos θ) is the Legendre function, and v is the order of the Legendre function; theta is the elevation angle of the corresponding coordinate of the position where the loudspeaker array element is located; theta₀Is P_v(cos θ) minimum zero;

S33B, simplifying calculation of a Legendre function, deducing a third-order polynomial to approximately express the weighting coefficient of each loudspeaker array element as follows:

in the formula (I), the compound is shown in the specification,

and S34B, outputting the beam with constant beam width by each loudspeaker array element according to the weighting coefficient.

Drawings

FIG. 1 shows a CBT array in step 3 according to the present invention;

fig. 2 is a schematic diagram of adjusting the directivity of the speaker array according to the present invention.

Detailed Description

The invention is further described below with reference to the accompanying drawings in combination with specific embodiments so that those skilled in the art can practice the invention with reference to the description, and the scope of the invention is not limited to the specific embodiments.

It will be understood by those skilled in the art that in the present disclosure, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like are used in an orientation or positional relationship indicated in the drawings for ease of description and simplicity of description, and do not indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and thus, the above terms should not be construed as limiting the present invention.

A sound field control method of a loudspeaker array comprises an upper computer and the loudspeaker array consisting of M loudspeaker array elements, wherein each loudspeaker array element is provided with a delayer, and the sound field control method comprises the following steps:

step 1, setting a loudspeaker array, and presetting a coverage angle theta of the loudspeaker array_-6db；

Step 2, according to the loudspeaker array and the coverage angle theta_-6dbObtaining a cut-off frequency F;

step 3, performing constant beam width control on the frequency section of the audio signal, which is smaller than the cut-off frequency F, by adopting a space resampling method; performing constant beam width control on a frequency segment of which the audio signal is greater than or equal to a cut-off frequency F by adopting a CBT array theory;

and 4, performing frequency division processing on the audio signals input into the loudspeaker array, and respectively transmitting the high-frequency signals and the low-frequency signals to the high-frequency unit and the low-frequency unit of the loudspeaker array element for output and play.

The cut-off frequency in the step 2 is as follows:

where H is the equivalent total length/m of the loudspeaker array based on CBT theory.

The step 3 of performing constant beam width control on the frequency segment smaller than the cut-off frequency F by using a spatial resampling method specifically includes:

S31A, dividing frequency segment into j frequency bands, and determining reference frequency f by using Chebyshev weighting method₀M loudspeaker elements with a weighting factor w₀(m)；

S32A, calculating other frequency bands f by a space resampling method_jWeighting coefficient w of the m-th loudspeaker array element_jThe formula (m) is as follows:

S33A. according to the weighting coefficient w_j(m) calculating the expected response of each loudspeaker array element filter by adopting a frequency response formula;

in the formula, w (f)_j) Is a design index of the filter;

S34A, solving filter coefficients corresponding to loudspeaker array elements by using a Least Square (LS) algorithm according to expected responses of the filters;

S35A, each loudspeaker array element outputs a beam with constant beam width according to the corresponding filter coefficient;

as shown in fig. 1, the step 3 of performing constant beam width control on the frequency segment greater than or equal to the cutoff frequency F by using the CBT array theory specifically includes:

S31B, adding delay factors of the delayers to each loudspeaker array element to enable the phase of the loudspeaker array to form an arc array with the radius r, wherein the delay factor tau meets the following requirements:

Φ＝(1-cos(θ_i))r

τ＝Φ/c

wherein c is the sound velocity of sound in air;

S32B, according to the CBT theory, the radial sound pressure distribution of the sound pressure of the frequency section, larger than or equal to the cut-off frequency F, of the arc array in the far and near fields meets the following requirements:

where ρ (θ) is a radial sound pressure distribution, P_v(cos θ) is the Legendre function, and v is the order of the Legendre function; theta is the elevation angle of the corresponding coordinate of the position where the loudspeaker array element is located; theta₀Is P_v(cos θ) minimum zero;

S33B, simplifying calculation of a Legendre function, deducing a third-order polynomial to approximately express the weighting coefficient of each loudspeaker array element as follows:

in the formula (I), the compound is shown in the specification,

and S34B, outputting the beam with constant beam width by each loudspeaker array element according to the weighting coefficient.

In addition, the directivity adjustment of the speaker array may be performed by sequentially applying a delay to each speaker array element, as shown in fig. 2, in this embodiment, the mirror images of each speaker are sequentially delayed by τ' at equal intervals from left to right, and the distance from each speaker array element to the wave front is just made up for the sound path difference between adjacent speaker array elements reaching the wave front, so that the sound waves emitted by each speaker array element can still reach the wave front after the directivity adjustment at the same time, and the direction perpendicular to the wave front is the main axis direction of the speaker array.

Time delay

In the formula, θ is a directivity adjustment angle of the front surface of the wave, d is a distance between the speaker array elements, and c is a propagation speed of sound in the air.