CN103916730A - Sound field focusing method and system capable of improving sound quality - Google Patents

Abstract

The invention relates to a sound field focusing method capable of improving sound quality. The method comprises the following steps: arranging a loudspeaker array and setting control points of a bright area and control points of a dark area, wherein the bright area is an area having high sound energy, and the dark area is an area having low sound energy; setting worst comparison focusing performance parameters and target vectors in the bright area on each frequency point; adjusting amplitude and phase of loudspeaker array input rehabilitation coefficient vectors on each frequency point by combining sound energy comparison control and least squares criterion according to the worst comparison focusing performance parameters and the target vectors in the bright area on each frequency point; and forming the rehabilitation coefficient vectors on each frequency point on each loudspeaker channel into a frequency response, windowing the frequency response and carrying out reverse Fourier transform to obtain a time-domain impulse response signal of each channel.

Description

A kind of sound field focusing method and system that can improve tonequality

Technical field

The present invention relates to field of acoustics, particularly a kind of sound field focusing method and system that can improve tonequality.

Background technology

Along with growth in the living standard, such as mobile phone, notebook, the personal consumption electronic products such as multimedia player are applied more and more extensive in life.User listens to the sound of this series products conventionally by earphone or loud speaker, but this can exist some problems, wears for a long time earphone and not only can make user feel under the weather, and also can damage hearing user, adopts loud speaker can bother user around.Adopt the personal audio system of loudspeaker array can effectively solve problems.Personal audio system can be assembled the region that comprises user by most of acoustic energy, thereby builds personalized private listening space for user.In personal audio system, the most frequently used controlling mechanism is acoustic energy compared with control method.By adjusting input signal phase place and the amplitude of the each passage of loudspeaker array, the ratio maximum of the acoustic energy that sound field compared with control method can make to comprise user area (being called area pellucida) and the acoustic energy of other irrelevant user region (being called dark space), thus reach the effect of focusing acoustic field.

But acoustic energy compared with control method of the prior art is only paid close attention to contrast focusing performance, do not focus on the tonequality problem in area pellucida, this may make the impression of user's audition decline, on the other hand, in some cases, after contrast focusing performance is greater than certain threshold value, people's subjectivity is focused on to impression impact little, and now more should pay close attention to tonequality problem, further to promote user's the impression of listening to.

Be not related to the problem of phonetic notation matter performance for only paying close attention to focusing performance in acoustic energy compared with control method of the prior art, need to find the better balance that more simple and effective method obtains tonequality and contrasts focusing performance.

Summary of the invention

The object of the invention is to overcome the problem of only paying close attention to focusing performance in existing acoustic energy compared with control method of the prior art and be not related to phonetic notation matter performance, thereby a kind of sound field focusing method that can improve tonequality is provided.

To achieve these goals, the invention provides a kind of sound field focusing method that can improve tonequality, comprising:

Step 1), lay loudspeaker array, set the control point of area pellucida and dark space; Wherein, described area pellucida is the region with high acoustic energy, and described dark space is the region with low acoustic energy;

Step 2), set the poorest contrast focusing performance parameter and the object vector in area pellucida on each Frequency point;

Step 3), according to step 2) the poorest contrast focusing performance parameter and the object vector in area pellucida on each Frequency point of obtaining, in conjunction with acoustic energy compared with control and least square method criterion, adjust respectively the phase and magnitude of the loudspeaker array input restore one's right coefficient vector on each Frequency point;

Step 4), by step 3) restore one's right coefficient vector component frequency response on each Frequency point in each loudspeaker channel of obtaining, to frequency response windowing, and carry out inverse Fourier transform, obtain the time domain impulse response signals of each passage.

In technique scheme, in step 1) in, the loudspeaker array laying is linear array or circular array or random array.

In technique scheme, in step 1) in, the region shape of described area pellucida or dark space is square or circular or line style.

In technique scheme, in described step 2) in, the poorest contrast focusing performance parameter of setting on each Frequency point comprises the following steps:

Step 2-1), determine a Frequency point f, obtain loudspeaker array divide the control point that is clipped to area pellucida and dark space at the transfer function matrix G at frequency f place _b,fand G _d,f, its size is respectively M _b× L and M _d× L, wherein M _band M _dbe respectively the control point number of area pellucida and dark space, L is number of loudspeakers;

Step 2-2), according to step 2-1) loudspeaker array that obtains divides the control point that is clipped to area pellucida and dark space at the transfer function matrix G at frequency f place _b,fand G _d,f, the maximum F of the ratio of calculating area pellucida and dark space acoustic energy _{max, f}; Wherein,

$F_{\max ,f}=\underset{w_f}{\max }\frac{M_D}{M_B}\frac{w_f^H{G}_{B,f}^H{G}_{B,f}{w}_f}{w_f^H(G_{D,f}^H,G_{D,f}+{\mathrm{\δ}}_{f}I)w_f}$

$=\frac{M_D}{M_B}{\mathrm{\λ}}_{\max }\left\{{(G_{D,f}^H{G}_{D,f}+{\mathrm{\δ}}_{f}I)}^{-1}{G}_{B,f}^H{G}_{B,f}\right\}$

Wherein λ _max{ } is the eigenvalue of maximum of matrix, δ _ffor robustness parameter, its selection range is unit matrix for being greater than 0, I, w _fit is the loudspeaker array input restore one's right coefficient vector on Frequency point f;

Step 2-3), by step 2-2) in the maximum F of ratio of area pellucida and dark space acoustic energy _{max, f}determine the poorest contrast focusing performance parameter J on Frequency point f _{min, f}span, its scope is (∞, F _{max, f}].

In technique scheme, at described step 2-1) in, adopt the audio-frequency test instruments such as B & K PULSE or obtain loudspeaker array by modeling and simulating and divide the control point that is clipped to area pellucida and dark space at the transfer function matrix G at frequency f place _b,fand G _d,f.

In technique scheme, in described step 2) in, the object vector d in the area pellucida on Frequency point f _frepresent, its size is L × 1, and the each element in vector equates and its value is arbitrary value.

In technique scheme, described step 3) comprise the following steps:

Step 3-1), utilize step 2) in set parameter F _{max, f}and d _f, in conjunction with acoustic energy compared with control and least square method criterion, list following optimal problem:

$\underset{w_f}{\min }{\left|\right|G_{B,f}{w}_f-d_f\left|\right|}^2$

$s.t.\frac{M_D}{M_B}\frac{w^H{G}_{B,f}^H{G}_{B,f}w}{w^H(G_{D,f}^H{G}_{D,f}+{\mathrm{\δ}}_{f}I)w}\≥J_{\min ,f}---\left(1\right)$

Step 3-2), order deployment step 3-1) expression formula that obtains, obtain:

$\underset{w_f}{\min }{w}_f^H{G}_{B,f}^H{G}_{B,f}{w}_f-2\mathrm{Re}\left\{w_f^H{G}_{B,f}^H{d}_f\right\}+d_f^H{d}_f$

$s.t.w_f^H[J_0(G_{D,f}^H{G}_{D,f}+{\mathrm{\δ}}_{f}I)-G_{B,f}^H{G}_{B,f}]w_f\≤0---\left(2\right)$

Wherein Re{} is the real part of getting element;

Step 3-3), be defined as follows:

$x=\left[\begin{array}{c}\mathrm{Re}\left\{w_f\right\}\\ \mathrm{Im}\left\{w_f\right\}\end{array}\right]$ $y=\left[\begin{array}{c}\mathrm{Re}\left\{G_{B,f}^H{d}_f\right\}\\ \mathrm{Im}\left\{G_{B,f}^H{d}_f\right\}\end{array}\right]$ $S=J_0(G_{D,f}^H{G}_{D,f}+{\mathrm{\δ}}_{f}I)-G_{B,f}^H{G}_{B,f}$

$H_1=\left[\begin{array}{cc}\mathrm{Re}\left\{G_{B,f}^H{G}_{B,f}\right\}& -\mathrm{Im}\left\{G_{B,f}^H{G}_{B,f}\right\}\\ \mathrm{Im}\left\{G_{B,f}^H{G}_{B,f}\right\}& \mathrm{Re}\left\{G_{B.,f}^H{G}_{B,f}\right\}\end{array}\right]$ $H_2=\left[\begin{array}{cc}\mathrm{Re}\left\{S\right\}& -\mathrm{Im}\left\{S\right\}\\ \mathrm{Im}\left\{S\right\}& \mathrm{Re}\left\{S\right\}\end{array}\right]---\left(3\right)$

Wherein Im{} is the imaginary part of getting element;

Step 3-4), by step 3-3) in defined expression formula substitution step 3-2) expression formula that obtains, thereby by step 3-2) in expression formula be converted to real number problem, and give up constant term obtain following expression:

$\underset{x}{\min }{x}^T{H}_{1}x-2y^{T}x$

s.t. x ^TH ₂x≤0 (4)

Step 3-5), by step 3-4) the Lagrangian dual problem of the optimal problem that expression formula is described that obtains is:

$\underset{\mathrm{\λ}}{\max }\underset{x}{\min }\mathrm{\ζ}(x,\mathrm{\λ})---\left(5\right)$

Wherein ζ (x, λ)=x ^th ₁x-2y ^tx+ λ x ^th ₂x;

Step 3-6), definition by step 3-5) described in dual problem be converted into following form, and then solve x;

$\begin{array}{cc}\underset{\mathrm{\λ}}{\max }& \mathrm{\γ}\\ & \mathrm{\λ}\≥0\\ s.t.& \left[\begin{array}{cc}{H}_1+\mathrm{\λ}{H}_2& -y\\ -y^T& -\mathrm{\γ}\end{array}\right]\≥0\end{array}---\left(6\right)$

Step 3-7), by step 3-6) value of the x that obtains is by step 3-3) described in expression formula be converted into final solution w _f.

In technique scheme, at described step 3-6) in, adopt protruding optimisation technique to obtain and separate x.

In technique scheme, in step 4) in, described window function is rectangular window or Hanning window or hamming window.

The present invention also provides a kind of sound field focusing system that can improve tonequality, comprising:

Loudspeaker array cloth amplification module, for laying loudspeaker array, sets the control point of area pellucida and dark space; Wherein, described area pellucida is the region with high acoustic energy, and described dark space is the region with low acoustic energy;

Just setting module of parameter, for setting the poorest contrast focusing performance parameter on each Frequency point and the object vector in area pellucida;

Input restore one's right coefficient vector adjusting module, for according to the poorest contrast focusing performance parameter on parameter each Frequency point that just setting module obtains with at the object vector in area pellucida, in conjunction with acoustic energy compared with control and least square method criterion, adjust respectively the phase and magnitude of the loudspeaker array input restore one's right coefficient vector on each Frequency point;

Time domain impulse response signals computing module, for the restore one's right coefficient vector component frequency response on each Frequency point in each loudspeaker channel that described input restore one's right coefficient vector adjusting module is obtained, to frequency response windowing, and carry out inverse Fourier transform, obtain the time domain impulse response signals of each passage.

The invention has the advantages that:

1, the present invention, by goal-selling vector, adopts all square minimum error principles, makes the frequency response in area pellucida approach the frequency response of desirable Dirac pulse, thereby has improved the tonequality in area pellucida.

2, the present invention can, by regulating the poorest contrast focusing performance parameter, obtain a good performance between contrast focusing performance and tonequality.

3, the sound field focusing method of improving tonequality of the present invention can be widely used in the personal audio fields such as television set, computer and mobile phone, by regulating the poorest contrast focusing performance parameter, between contrast focusing performance and tonequality, can obtain a good performance.

Accompanying drawing explanation

Fig. 1 is the flow chart of the sound field focusing method of improving tonequality based in conjunction with acoustic energy compared with control and least square method of the present invention;

Fig. 2 is in one embodiment, the schematic diagram of linear loudspeaker array;

Fig. 3 is the inventive method and the acoustic energy compared with control method of the prior art schematic diagram at the contrast focusing performance of different frequency point;

Fig. 4 (a) is the schematic diagram of the inventive method at the impulse response at control point place, center, area pellucida;

Fig. 4 (b) is the schematic diagram of acoustic energy compared with control method of the prior art at the impulse response at control point place, center, area pellucida.

Embodiment

Now the invention will be further described by reference to the accompanying drawings.

Basic thought of the present invention is the poorest default contrast focusing performance parameter, in the situation that guaranteeing that contrast focusing performance is not less than this parameter, utilize default object vector, make the frequency response in area pellucida approach the frequency response of desirable Dirac-delta pulse, thereby improve acoustical quality, and can be by regulating the poorest contrast focusing performance parameter to obtain the balance between contrast focusing performance and tonequality.

With reference to figure 1, the sound field focusing method of improving tonequality based in conjunction with acoustic energy compared with control and least square method of the present invention comprises the following steps:

Step 1), lay loudspeaker array, set the control point of area pellucida and dark space; Wherein, described area pellucida is the region with high acoustic energy, and described dark space is the region with low acoustic energy;

Step 2), set the poorest contrast focusing performance parameter and the object vector in area pellucida on each Frequency point;

Step 3), in conjunction with acoustic energy compared with control and least square method criterion, adjust respectively the phase and magnitude of loudspeaker array on each Frequency point input restore one's right coefficient vector;

Step 4), by step 3) restore one's right coefficient vector component frequency response on each Frequency point in each loudspeaker channel of obtaining, to frequency response windowing, and carry out inverse Fourier transform, obtain the time domain impulse response signals of each passage.

Below each step in the inventive method is described further.

In step 1) in, the loudspeaker array laying is linear array or circular array, can be also random array.The region shape of described area pellucida or dark space can be square or circular, can be also line style.

In described step 2) in, the poorest contrast focusing performance parameter of setting on each Frequency point comprises the following steps:

Step 2-1), determine a Frequency point f, adopt the audio-frequency test instruments such as B & K PULSE or obtain loudspeaker array by modeling and simulating and divide the control point that is clipped to area pellucida and dark space at the transfer function matrix G at frequency f place _b,fand G _d,f, its size is respectively M _b× L and M _d× L, wherein M _band M _dbe respectively the control point number of area pellucida and dark space, L is number of loudspeakers;

Step 2-2), according to step 2-1) loudspeaker array that obtains divides the control point that is clipped to area pellucida and dark space at the transfer function matrix G at frequency f place _b,fand G _d,f, the maximum F of the ratio of calculating area pellucida and dark space acoustic energy _{max, f}.Wherein,

$F_{\max ,f}=\underset{w_f}{\max }\frac{M_D}{M_B}\frac{w_f^H{G}_{B,f}^H{G}_{B,f}{w}_f}{w_f^H(G_{D,f}^H,G_{D,f}+{\mathrm{\δ}}_{f}I)w_f}$

$=\frac{M_D}{M_B}{\mathrm{\λ}}_{\max }\left\{{(G_{D,f}^H{G}_{D,f}+{\mathrm{\δ}}_{f}I)}^{-1}{G}_{B,f}^H{G}_{B,f}\right\}$

Wherein λ _max{ } is the eigenvalue of maximum of matrix, δ _ffor robustness parameter, its selection range is unit matrix for being greater than 0, I, w _fit is the loudspeaker array input restore one's right coefficient vector on Frequency point f;

Step 2-3), by step 2-2) in the maximum F of ratio of area pellucida and dark space acoustic energy _{max, f}determine the poorest contrast focusing performance parameter J on Frequency point f _{min, f}span, its scope is (∞, F _{max, f}].

In described step 2) in, the object vector d in the area pellucida on Frequency point f _frepresent, its size is L × 1, and the each element in vector equates and its value can be arbitrary value.

Described step 3) specifically comprise the following steps:

Step 3-1), utilize step 2) in set parameter F _{max, f}and d _f, in conjunction with acoustic energy compared with control and least square method criterion, list following optimal problem:

$\underset{w_f}{\min }{\left|\right|G_{B,f}{w}_f-d_f\left|\right|}^2$

$s.t.\frac{M_D}{M_B}\frac{w^H{G}_{B,f}^H{G}_{B,f}w}{w^H(G_{D,f}^H{G}_{D,f}+{\mathrm{\δ}}_{f}I)w}\≥J_{\min ,f}---\left(1\right)$

Step 3-2), order deployment step 3-1) expression formula that obtains, obtain:

$\underset{w_f}{\min }{w}_f^H{G}_{B,f}^H{G}_{B,f}{w}_f-2\mathrm{Re}\left\{w_f^H{G}_{B,f}^H{d}_f\right\}+d_f^H{d}_f$

$s.t.w_f^H[J_0(G_{D,f}^H{G}_{D,f}+{\mathrm{\δ}}_{f}I)-G_{B,f}^H{G}_{B,f}]w_f\≤0---\left(2\right)$

Wherein Re{} is the real part of getting element;

Step 3-3), be defined as follows:

$x=\left[\begin{array}{c}\mathrm{Re}\left\{w_f\right\}\\ \mathrm{Im}\left\{w_f\right\}\end{array}\right]$ $y=\left[\begin{array}{c}\mathrm{Re}\left\{G_{B,f}^H{d}_f\right\}\\ \mathrm{Im}\left\{G_{B,f}^H{d}_f\right\}\end{array}\right]$ $S=J_0(G_{D,f}^H{G}_{D,f}+{\mathrm{\δ}}_{f}I)-G_{B,f}^H{G}_{B,f}$

$H_1=\left[\begin{array}{cc}\mathrm{Re}\left\{G_{B,f}^H{G}_{B,f}\right\}& -\mathrm{Im}\left\{G_{B,f}^H{G}_{B,f}\right\}\\ \mathrm{Im}\left\{G_{B,f}^H{G}_{B,f}\right\}& \mathrm{Re}\left\{G_{B.,f}^H{G}_{B,f}\right\}\end{array}\right]$ $H_2=\left[\begin{array}{cc}\mathrm{Re}\left\{S\right\}& -\mathrm{Im}\left\{S\right\}\\ \mathrm{Im}\left\{S\right\}& \mathrm{Re}\left\{S\right\}\end{array}\right]---\left(3\right)$

Wherein Im{} is the imaginary part of getting element;

Step 3-4), by step 3-3) in defined expression formula substitution step 3-2) expression formula that obtains, thereby by step 3-2) in expression formula be converted to real number problem, and give up constant term obtain following expression:

$\underset{x}{\min }{x}^T{H}_{1}x-2y^{T}x$

s.t. x ^TH ₂x≤0 (4)

Step 3-5), by step 3-4) the Lagrangian dual problem of the optimal problem that expression formula is described that obtains is:

$\underset{\mathrm{\λ}}{\max }\underset{x}{\min }\mathrm{\ζ}(x,\mathrm{\λ})---\left(5\right)$

Wherein ζ (x, λ)=x ^th ₁x-2y ^tx+ λ x ^th ₂x;

Step 3-6), definition by step 3-5) described in dual problem be converted into following form, and then solve x.

$\begin{array}{cc}\underset{\mathrm{\λ}}{\max }& \mathrm{\γ}\\ & \mathrm{\λ}\≥0\\ s.t.& \left[\begin{array}{cc}{H}_1+\mathrm{\λ}{H}_2& -y\\ -y^T& -\mathrm{\γ}\end{array}\right]\≥0\end{array}---\left(6\right)$

This problem is a positive semidefinite optimization problem, can be obtained and be separated x by the technology such as protruding optimization.

Step 3-7), by step 3-6) value of the x that obtains is by step 3-3) described in expression formula be converted into final solution w _f.

In step 4) in, described window function can be rectangular window, can be also Hanning window or hamming window.

For a better understanding of the present invention, below in conjunction with the drawings and specific embodiments, the present invention is described in further detail:

In the present embodiment, as shown in Figure 2, in Acoustical Inst., Chinese Academy of Sciences's whole elimination room, place a linear loudspeaker array, loudspeaker array is made up of 8 moving-coil type favour prestige loud speakers, and spacing is 12cm, loudspeaker unit maximum power is 15W, rated impedance 8 Ω; Area pellucida and dark space are on loudspeaker array perpendicular bisector the each 45 degree directions in left and right, are all 1m apart from loudspeaker array spacing, and with loudspeaker array in same level; The control point of area pellucida and dark space is all defined by 5 yuan of microphone arrays, is spaced apart 8cm, and microphone is 4189 microphones of B & K company of Denmark; The hardware unit that experiment is selected is power amplifier, PULSE measuring instrument and PC.

The specific implementation process of the present embodiment comprises the following steps:

(1) systematic sampling rate f _sbe made as 8kHz, the length N of time domain impulse response signals is made as 800, and the calculated rate point of selection is for 10Hz is to 3920Hz, and frequency interval is 10Hz.First measure loudspeaker array and divide the transfer function matrix that is clipped to area pellucida and control point, dark space at each Frequency point, this can be by adopting PULSE instrument directly to measure the frequency response function of loudspeaker array to each control point, then Matlab software frequency response being imported on PC platform is processed, can a step must all frequencies transfer function matrix G _b,fand G _d,f.

(2) secondly, set the poorest contrast focusing performance parameter J of all Frequency points _minbe all 10, at Frequency point f place, target setting vector is

(3) being set in all Frequency point robustness parameters is all 0.001, according to calculating in conjunction with acoustic energy compared with control and least square method criterion the restore one's right coefficient vector w that optimum loudspeaker array is inputted _f, be then combined into frequency response, and it added to rectangular window and do inverse Fourier transform and obtain the time domain impulse response signals of respective channel.

Fig. 3 has provided the inventive method and the acoustic energy compared with control method of the prior art contrast focusing performance at different frequency point, as can be seen from the figure, on selected Frequency point, although the contrast focusing performance of the inventive method declines, can guarantee to be greater than the poorest default contrast focusing performance 10log10 (J _{min, f}), from the acoustical testing mentioned hereinafter, can find out, although contrast focusing performance declines, tonequality is improved.

Fig. 4 has provided respectively the inventive method (Fig. 4 (a)) and acoustic energy compared with control method of the prior art (Fig. 4 (the b)) impulse response at control point place, center, area pellucida.Relatively two width figure can find out, acoustic energy control method oscillation amplitude of the prior art is large, conditions of streaking is serious, and the impulse response that adopts the inventive method to obtain more approaches desirable Dirac-delta pulse, therefore can greatly improve tonequality, this is to contrast the obtainable tonequality of focusing by sacrifice to improve.

Improving tonequality can assess by PESQ (Perceptual evaluation of speech quality) mark, the score value of PESQ is between 0 to 4.5 point, 0 representative is the poorest, and 4.5 represent preferably, and voice after treatment and former voice only have pure delay.Here two voice signal sample rates that adopt are 8kHz, called after e1 and e2 respectively, the content of e1 and e2 is respectively " the birch canoe slid on the smooth planks " and " glue the sheet to the dark blue background ", is read aloud by male voice.Table 1 has provided the speech quality PESQ mark that control point place, center, area pellucida produces, as can be seen from the table, acoustic energy compared with control method of the prior art has infringement to speech quality, and than acoustic energy compared with control method of the prior art, the inventive method has greatly been improved speech quality, almost speech quality can be reverted to the tonequality of raw tone.

The speech quality evaluation that control point, center, table 1 area pellucida place produces, adopts PESQ mark

	The inventive method	Method of the prior art
			e1	4.3317	2.9238
e2	4.3179	2.9073

Be 8kHz although define sample frequency in the present embodiment, and selected area pellucida and dark space are linear regions, but this is only that one of method provided by the present invention is illustrated, not limiting method provided by the present invention is only suitable in people's voice frequency range, or area pellucida, line style can only be selected in dark space.In fact, method provided by the present invention can be extended to the broadband signal of whole audio frequency section and realize acoustic energy contrast and focus on.

The present invention also provides a kind of sound field focusing system that can improve tonequality identical with preceding method, comprising:

Loudspeaker array cloth amplification module, for laying loudspeaker array, sets the control point of area pellucida and dark space; Wherein, described area pellucida is the region with high acoustic energy, and described dark space is the region with low acoustic energy;

Just setting module of parameter, for setting the poorest contrast focusing performance parameter on each Frequency point and the object vector in area pellucida;

Input restore one's right coefficient vector adjusting module, for according to the poorest contrast focusing performance parameter on parameter each Frequency point that just setting module obtains with at the object vector in area pellucida, in conjunction with acoustic energy compared with control and least square method criterion, adjust respectively the phase and magnitude of the loudspeaker array input restore one's right coefficient vector on each Frequency point;

Time domain impulse response signals computing module, for the restore one's right coefficient vector component frequency response on each Frequency point in each loudspeaker channel that described input restore one's right coefficient vector adjusting module is obtained, to frequency response windowing, and carry out inverse Fourier transform, obtain the time domain impulse response signals of each passage.

It should be noted last that, above embodiment is only unrestricted in order to technical scheme of the present invention to be described.Although the present invention is had been described in detail with reference to embodiment, those of ordinary skill in the art is to be understood that, technical scheme of the present invention is modified or is equal to replacement, do not depart from the spirit and scope of technical solution of the present invention, it all should be encompassed in the middle of claim scope of the present invention.

Claims (10)

1. the sound field focusing method that can improve tonequality, comprising:

Step 1), lay loudspeaker array, set the control point of area pellucida and dark space; Wherein, described area pellucida is the region with high acoustic energy, and described dark space is the region with low acoustic energy;

Step 2), set the poorest contrast focusing performance parameter and the object vector in area pellucida on each Frequency point;

Step 3), according to step 2) the poorest contrast focusing performance parameter and the object vector in area pellucida on each Frequency point of obtaining, in conjunction with acoustic energy compared with control and least square method criterion, adjust respectively the phase and magnitude of the loudspeaker array input restore one's right coefficient vector on each Frequency point;

Step 4), by step 3) restore one's right coefficient vector component frequency response on each Frequency point in each loudspeaker channel of obtaining, to frequency response windowing, and carry out inverse Fourier transform, obtain the time domain impulse response signals of each passage.

2. the sound field focusing method that can improve tonequality according to claim 1, is characterized in that, in step 1) in, the loudspeaker array laying is linear array or circular array or random array.

3. the sound field focusing method that can improve tonequality according to claim 1, is characterized in that, in step 1) in, the region shape of described area pellucida or dark space is square or circular or line style.

4. the sound field focusing method that can improve tonequality according to claim 1, is characterized in that, in described step 2) in, the poorest contrast focusing performance parameter of setting on each Frequency point comprises the following steps:

Step 2-1), determine a Frequency point f, obtain loudspeaker array divide the control point that is clipped to area pellucida and dark space at the transfer function matrix G at frequency f place _b,fand G _d,f, its size is respectively M _b× L and M _d× L, wherein M _band M _dbe respectively the control point number of area pellucida and dark space, L is number of loudspeakers;

Step 2-2), according to step 2-1) loudspeaker array that obtains divides the control point that is clipped to area pellucida and dark space at the transfer function matrix G at frequency f place _b,fand G _d,f, the maximum F of the ratio of calculating area pellucida and dark space acoustic energy _{max, f}; Wherein,

$F_{\max ,f}=\underset{w_f}{\max }\frac{M_D}{M_B}\frac{w_f^H{G}_{B,f}^H{G}_{B,f}{w}_f}{w_f^H(G_{D,f}^H,G_{D,f}+{\mathrm{\δ}}_{f}I)w_f}$

$=\frac{M_D}{M_B}{\mathrm{\λ}}_{\max }\left\{{(G_{D,f}^H{G}_{D,f}+{\mathrm{\δ}}_{f}I)}^{-1}{G}_{B,f}^H{G}_{B,f}\right\}$

Wherein λ _max{ } is the eigenvalue of maximum of matrix, δ _ffor robustness parameter, its selection range is unit matrix for being greater than 0, I, w _fit is the loudspeaker array input restore one's right coefficient vector on Frequency point f;

Step 2-3), by step 2-2) in the maximum F of ratio of area pellucida and dark space acoustic energy _{max, f}determine the poorest contrast focusing performance parameter J on Frequency point f _{min, f}span, its scope is (∞, F _{max, f}].

5. the sound field focusing method that can improve tonequality according to claim 4, it is characterized in that, at described step 2-1) in, adopt the audio-frequency test instruments such as B & K PULSE or obtain loudspeaker array by modeling and simulating and divide the control point that is clipped to area pellucida and dark space at the transfer function matrix G at frequency f place _b,fand G _d,f.

6. the sound field focusing method that can improve tonequality according to claim 4, is characterized in that, in described step 2) in, the object vector d in the area pellucida on Frequency point f _frepresent, its size is L × 1, and the each element in vector equates and its value is arbitrary value.

7. the sound field focusing method that can improve tonequality according to claim 6, is characterized in that described step 3) comprise the following steps:

Step 3-1), utilize step 2) in set parameter F _{max, f}and d _f, in conjunction with acoustic energy compared with control and least square method criterion, list following optimal problem:

$\underset{w_f}{\min }{\left|\right|G_{B,f}{w}_f-d_f\left|\right|}^2$

$s.t.\frac{M_D}{M_B}\frac{w^H{G}_{B,f}^H{G}_{B,f}w}{w^H(G_{D,f}^H{G}_{D,f}+{\mathrm{\δ}}_{f}I)w}\≥J_{\min ,f}---\left(1\right)$

Step 3-2), order deployment step 3-1) expression formula that obtains, obtain:

$\underset{w_f}{\min }{w}_f^H{G}_{B,f}^H{G}_{B,f}{w}_f-2\mathrm{Re}\left\{w_f^H{G}_{B,f}^H{d}_f\right\}+d_f^H{d}_f$

$s.t.w_f^H[J_0(G_{D,f}^H{G}_{D,f}+{\mathrm{\δ}}_{f}I)-G_{B,f}^H{G}_{B,f}]w_f\≤0---\left(2\right)$

Wherein Re{} is the real part of getting element;

Step 3-3), be defined as follows:

$x=\left[\begin{array}{c}\mathrm{Re}\left\{w_f\right\}\\ \mathrm{Im}\left\{w_f\right\}\end{array}\right]$ $y=\left[\begin{array}{c}\mathrm{Re}\left\{G_{B,f}^H{d}_f\right\}\\ \mathrm{Im}\left\{G_{B,f}^H{d}_f\right\}\end{array}\right]$ $S=J_0(G_{D,f}^H{G}_{D,f}+{\mathrm{\δ}}_{f}I)-G_{B,f}^H{G}_{B,f}$

$H_1=\left[\begin{array}{cc}\mathrm{Re}\left\{G_{B,f}^H{G}_{B,f}\right\}& -\mathrm{Im}\left\{G_{B,f}^H{G}_{B,f}\right\}\\ \mathrm{Im}\left\{G_{B,f}^H{G}_{B,f}\right\}& \mathrm{Re}\left\{G_{B.,f}^H{G}_{B,f}\right\}\end{array}\right]$ $H_2=\left[\begin{array}{cc}\mathrm{Re}\left\{S\right\}& -\mathrm{Im}\left\{S\right\}\\ \mathrm{Im}\left\{S\right\}& \mathrm{Re}\left\{S\right\}\end{array}\right]---\left(3\right)$

Wherein Im{} is the imaginary part of getting element;

Step 3-4), by step 3-3) in defined expression formula substitution step 3-2) expression formula that obtains, thereby by step 3-2) in expression formula be converted to real number problem, and give up constant term obtain following expression:

$\underset{x}{\min }{x}^T{H}_{1}x-2y^{T}x$

s.t. x ^TH ₂x≤0 (4)

Step 3-5), by step 3-4) the Lagrangian dual problem of the optimal problem that expression formula is described that obtains is:

$\underset{\mathrm{\λ}}{\max }\underset{x}{\min }\mathrm{\ζ}(x,\mathrm{\λ})---\left(5\right)$

Wherein ζ (x, λ)=x ^th ₁x-2y ^tx+ λ x ^th ₂x;

Step 3-6), definition by step 3-5) described in dual problem be converted into following form, and then solve x;

$\begin{array}{cc}\underset{\mathrm{\λ}}{\max }& \mathrm{\γ}\\ & \mathrm{\λ}\≥0\\ s.t.& \left[\begin{array}{cc}{H}_1+\mathrm{\λ}{H}_2& -y\\ -y^T& -\mathrm{\γ}\end{array}\right]\≥0\end{array}---\left(6\right)$

Step 3-7), by step 3-6) value of the x that obtains is by step 3-3) described in expression formula be converted into final solution w _f.

8. the sound field focusing method that can improve tonequality according to claim 7, is characterized in that, at described step 3-6) in, adopt protruding optimisation technique to obtain and separate x.

9. the sound field focusing method that can improve tonequality according to claim 1, is characterized in that, in step 4) in, described window function is rectangular window or Hanning window or hamming window.

10. the sound field focusing system that can improve tonequality, is characterized in that, comprising:

Loudspeaker array cloth amplification module, for laying loudspeaker array, sets the control point of area pellucida and dark space; Wherein, described area pellucida is the region with high acoustic energy, and described dark space is the region with low acoustic energy;

Just setting module of parameter, for setting the poorest contrast focusing performance parameter on each Frequency point and the object vector in area pellucida;

Input restore one's right coefficient vector adjusting module, for according to the poorest contrast focusing performance parameter on parameter each Frequency point that just setting module obtains with at the object vector in area pellucida, in conjunction with acoustic energy compared with control and least square method criterion, adjust respectively the phase and magnitude of the loudspeaker array input restore one's right coefficient vector on each Frequency point;

Time domain impulse response signals computing module, for the restore one's right coefficient vector component frequency response on each Frequency point in each loudspeaker channel that described input restore one's right coefficient vector adjusting module is obtained, to frequency response windowing, and carry out inverse Fourier transform, obtain the time domain impulse response signals of each passage.