CN100578622C - A kind of adaptive microphone array system and audio signal processing method thereof - Google Patents
A kind of adaptive microphone array system and audio signal processing method thereof Download PDFInfo
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Abstract
The invention discloses a kind of adaptive microphone array system and audio signal processing method thereof, upgrade control module by in microphone array system, increasing adaptive filter coefficient, employed step value when whether the control sef-adapting filter carries out coefficient update or adaptive filter coefficient renewal, make the coefficient update of sef-adapting filter only carry out at noise, thereby avoided when the noise composition that is comprised in the signal from the rear with can compare from the phonetic element in the place ahead or during much smaller than phonetic element, when utilizing the self-adaptation first order difference microphone array system of prior art to carry out filter coefficient update, spinoffs such as efficient voice signal amplitude appear reducing.Adopt the high-order sef-adapting filter in the adaptive microphone array system of the present invention, with the adjustment criterion of maximum reduction noise magnitude as adaptive filter coefficient, make when having a plurality of noise source, no matter actual sensing at system's zero point where, can the assurance system obtain best denoising effect.
Description
Technical field
The present invention relates to voice processing technology, particularly a kind of adaptive microphone array system and audio signal processing method thereof.
Background technology
In real-life situation, be full of various noises and echo, the proper communication that these interference can have a strong impact on people exchanges, and also can reduce the usefulness of speech recognition system, and a kind of settling mode just is to use microphone array system.First order difference microphone array system commonly used adopts beam forming technique, utilizes two non-directive microphones to form two back-to-back heart-shaped directive property Mikes.Microphone array not only can overcome environmental noise and the echo influence to voice signal, restores clean voice, and can record at a distance, rejects most of environmental noise in recording, solves wear-type Mike inconvenient problem with use.And this microphone array technology is not at the specific noise environment, and it goes for obtaining gratifying effect under any noisy environment.
Referring to Fig. 1, Fig. 1 is the structured flowchart of the self-adaptation first order difference microphone array system of prior art.As shown in Figure 1, this system comprises fixed directional beam shaping module 101, single order sef-adapting filter 102 and totalizer 103.
Wherein fixed directional beam shaping module 101 comprises time delay module 106 that aphalangia delays time to Mike B105, signal b (k) that Mike B is gathered to Mike A104 and aphalangia, is used for time delay module 108 and totalizer 107 and 109 that the signal f (k) that Mike A gathers is delayed time.
Mike A104 and Mike B105 form pattern back-to-back, and the distance between two Mikes is d, and hypothesis Mike A104 be preposition Mike over against target speaker mouth, be the dead ahead with this direction, i.e. 0 degree direction; Mike B be rearmounted Mike back to target speaker mouth, be the dead astern with this direction, promptly 180 the degree angular direction. Time delay module 106 and 108 delay time are d/c, and c is the velocity of sound.Totalizer 107 be used to calculate f (k) and b (k) time delayed signal reverse and; Totalizer 109 be used to calculate b (k) and f (k) time delayed signal reverse and.
Utilize system shown in Figure 1 to carry out the process flow diagram that voice signal is handled, as shown in Figure 2, this flow process may further comprise the steps:
Step 201, fixed directional beam shaping module 101 adopts two back-to-back non-directive Mike A104 and Mike B105, utilizes beam forming technique to constitute heart-shaped directive property Mike.Concrete steps comprise: the signal f (k) that collects with Mike A104 deducts the time delayed signal b (k-d/c) of the signal b (k) that Mike B105 collects, obtains the output signal x that principal ingredient is the voice signal of the place ahead incident (k).Simultaneously, the time delayed signal f (k-d/c) with b (k) deducts f (k) obtains the output signal n that principal ingredient is the noise signal of rear incident (k), thereby forms heart-shaped directive property Mike.
Heart-shaped directive property Mike is a kind of microphone of fixed directional, the zero point of its polar mode (polarpattern) is all the time towards the dead astern, the noise that the noise source that promptly main weakening is positioned at the dead astern is sent, the direction that needs to weaken signal is pointed to 180 degree directions all the time, and in the actual noisy environment, therefore the position of noise source might not need to adjust by adaptive filter coefficient w (k) the polar mode zero point of microphone array system in the dead astern.
Step 202, single order sef-adapting filter 102 adopts the adaptive filter coefficient update algorithm to calculate adaptive filter coefficient w (k), and utilize result of calculation to adjust the polar mode zero point of microphone array system, utilize formula n ' (k)=w (k) n (k), calculate (k), and the result is sent to totalizer 103 after oppositely with the estimated value n ' of the residual noise signal among the x (k) of n (k) simulation.Wherein, the polar mode θ at zero point of the value of adaptive filter coefficient w (k) and microphone array system
NullRelation be approximately:
(k) reverse of the estimated value n ' that step 203, totalizer 103 are calculated the residual noise signal that obtains in x (k) and the step 202 and, draw residual signals s (k), and with s (k) as k output signal constantly.Simultaneously, this output signal s (k) is sent into sef-adapting filter as feedback signal,, improve the quality of voice signal by the polar mode zero point of further adjustment microphone array system.
Owing to can not realize the coefficient update of wave filter is controlled in the said method, so have only when from the noise signal at rear during much larger than voice signal, utilize said system and method just the noise composition among the x (k) can be filtered out, can not cause negative effect simultaneously the voice signal among the x (k).And when the noise composition is very little in from the signal at rear, there be not sounding sometime such as noise source, because the imperfection of beam shaping, the amplitude of the efficient voice signal content among the n (k) may be suitable with noise signal, even much larger than the amplitude of noise signal, carrying out filter coefficient update according to said system and method this moment can make the polar mode of system adjust to the dead ahead zero point, it is source speech signal place direction, the spinoff of efficient voice amplitude appears reducing, as speech volume is diminished, voice fog, and echo etc. occurs.
In addition, said method uses the single order sef-adapting filter as postfilter, though can realize the self-adaptation adjustment at polar mode zero point of microphone array system in theory,, can obtain denoising effect preferably at zero point when certain noise source is in this during the orientation really.But when having a plurality of noise source simultaneously, this method with system's 0:00 direction sensing noise source is infeasible in theory, because zero point is corresponding a plurality of noise sources simultaneously, and noise source generally is not unique in the actual environment, and simple multiple relation between noise composition among the output signal x (k) and the n (k), therefore consider from the angle of sef-adapting filter performance, use the single order sef-adapting filter not reach the purpose of the noise contribution among the filtering x (k) substantially.
Summary of the invention
In view of this, fundamental purpose of the present invention is to provide a kind of adaptive microphone array system, and this system can control adaptive filter coefficient updates, solves the problem that reduces the efficient voice signal amplitude.
In view of this, another object of the present invention is to provide a kind of audio signal processing method of adaptive microphone array, this method can be controlled adaptive filter coefficient updates, solves the problem that reduces the efficient voice signal amplitude.
First aspect to achieve these goals, the invention provides a kind of adaptive microphone array system, this system comprises that the fixed directional wave beam forms module, sef-adapting filter, arithmetical unit, described fixed directional wave beam forms module and is used for two back-to-back non-directive Mikes are formed heart-shaped directive property Mike, this system comprises that further adaptive filter coefficient upgrades control module
Adaptive filter coefficient upgrades control module, be energy comparer or sef-adapting filter step-length control module, forming module with the fixed directional wave beam links to each other, receive the fixed directional wave beam form module output based on the signal of the place ahead incident voice signal and based on the signal of the noise signal of rear incident, and send adaptive filter coefficient according to the relative size of two-way output signal energy to sef-adapting filter and upgrade control signal, whether the control sef-adapting filter carries out the step value of coefficient update or coefficient update correspondence;
Described sef-adapting filter, determine to carry out the step value of coefficient update or coefficient update correspondence according to the coefficient update control signal that receives, the usage factor update algorithm is determined the coefficient vector of the sef-adapting filter of current time, coefficient vector in conjunction with the sef-adapting filter of determining, the principal ingredient that forms module output with the fixed directional wave beam is the signal of the noise signal of rear incident, simulates the residual noise signal in the signal that the principal ingredient of exporting is the place ahead incident voice signal;
Described arithmetical unit is used for more described principal ingredient and is the residual noise signal of this signal of the signal of the place ahead incident voice signal and simulation, obtains residual signals.
Described sef-adapting filter is the sub-band adaptive wave filter; It is one or more that described adaptive filter coefficient upgrades control module, and the number that adaptive filter coefficient upgrades control module is identical with sub band number.
It is energy comparer or sef-adapting filter step-length control module that described adaptive filter coefficient upgrades control module.
Described sef-adapting filter is higher-Order Time-Domain sef-adapting filter or high-order adaptive frequency domain filter.
This adaptive microphone array system further comprises time delay module, this module forms module with described fixed directional wave beam and links to each other with arithmetical unit, sends to described arithmetical unit after being used for the signal that described voice signal with the place ahead incident is a principal ingredient delayed time.
When described sef-adapting filter was the linear phase sef-adapting filter, the delay time of described time delay module was half of described sef-adapting filter exponent number.
Described arithmetical unit is totalizer or subtracter.
Second aspect to achieve these goals the invention provides a kind of audio signal processing method of adaptive microphone array, and this method may further comprise the steps:
A, utilize beam forming technique to constitute heart-shaped directive property Mike two back-to-back non-directive Mikes;
B, according to fixed directional beam shaping module output based on the signal energy of the place ahead incident voice signal and relative size, to sef-adapting filter transmission adaptive filter coefficient renewal control signal based on the signal energy of the noise signal of rear incident;
C, sef-adapting filter are according to the control signal that receives, when determining to carry out the step value of coefficient update or coefficient update correspondence, the usage factor update algorithm is determined the adaptive filter coefficient vector of current time, then in conjunction with the adaptive filter coefficient vector of determining, with the signal based on the noise signal of rear incident of fixed directional beam shaping module output, simulate based on the residual noise signal in the signal of the place ahead incident voice signal;
The residual noise signal to simulate among the signal of the place ahead incident voice signal and the step C of D, the output of contrast fixed directional beam shaping module obtains residual signals.
The described transmission adaptive filter coefficient of step B upgrades control signal: when being mainly the noise signal of rear incident in the signal that described Mike collects, send renewal adaptive filter coefficient updates control signal to sef-adapting filter; Otherwise transmission stops to upgrade the adaptive filter coefficient updates control signal.
The described noise signal that is mainly rear incident by the ratio of the noise energy of the speech energy of the place ahead incident and rear incident is determined upgrade the adaptive filter coefficient updates control signal if the ratio of the two greater than preset threshold value, then sends; Otherwise transmission stops to upgrade the adaptive filter coefficient updates control signal.
The step value of correspondence that the described transmission adaptive filter coefficient of step B upgrades control signal when upgrading for sending the adaptive filter coefficient vector, described step value is definite with the ratio of the noise energy of rear incident by the speech energy of the place ahead incident.
The step value μ of described coefficient update correspondence is:
μ wherein
RefThe reference step-length of be setting, the reference energy ratio of ratio_ref for setting, ratio_env (k) be the ratio of the noise energy of the speech energy of k moment the place ahead incident and rear incident.
Step D is described further to be comprised after drawing residual signals: described residual signals is sent into sef-adapting filter, and sef-adapting filter is further adjusted adaptive filter coefficient according to the coefficient update control signal that next receives constantly.
When described sef-adapting filter is the single order sef-adapting filter, step C is described with the place ahead incident voice signal be in the signal of principal ingredient the residual noise signal to be estimated as with rear incident noise signal be the signal of principal ingredient and the product of single order adaptive filter coefficient.
When described sef-adapting filter is the high-order sef-adapting filter, the described simulation of step C is that the residual noise signal in the signal of principal ingredient serves as in conjunction with being the signal of principal ingredient and the coefficient vector of determined sef-adapting filter with rear incident noise signal with the place ahead incident voice signal, estimates described residual noise signal with linear convolution.
Step D is described to be that the signal of principal ingredient serves as through the signal after the time-delay with the place ahead incident voice signal.
When described sef-adapting filter was the linear phase sef-adapting filter, described delay time was half of sef-adapting filter exponent number.
Step C is described to determine to carry out the step value of coefficient update or coefficient update correspondence for determining once every Fixed Time Interval.
By technical scheme of the present invention as seen, this adaptive microphone array system of the present invention and audio signal processing method thereof, upgrade control module by in microphone array system, increasing adaptive filter coefficient, two paths of signals to the output of fixed directional beam shaping module compares, and according to comparative result output filter coefficient update control signal to sef-adapting filter, whether the control adaptive filter coefficient upgrades or adaptive filter coefficient employed step value when upgrading, when thereby the self-adaptation first order difference microphone array system of having avoided utilizing prior art carries out filter coefficient update, the noise composition that in signal, is comprised from the rear with can compare or under the situation of phonetic element from the phonetic element in the place ahead, the efficient voice signal amplitude occurs reducing, introduce spinoffs such as voice distortion.
In addition, sef-adapting filter in adaptive microphone array system of the present invention and the audio signal processing method thereof adopts the high-order sef-adapting filter, compare with the single order sef-adapting filter, the high-order sef-adapting filter has better filtering and noise reduction effect, high-order sef-adapting filter length is long more, and analog capability is strong more.High-order sef-adapting filter of the present invention is simulated noise composition among the x (k) with a linear convolution process, directly pursue the output signal-noise ratio maximization, it is maximum filter out noise composition, make when having a plurality of noise source, no matter actual sensing at system's zero point where, can the assurance system obtain best denoising effect.
With just output behind the place ahead output signal time-delay T, guaranteed the causality of sef-adapting filter in adaptive microphone array system of the present invention and the audio signal processing method thereof.Simultaneously for fear of introducing unnecessary time-delay, the present invention adopts linear phase adaptation wave filter, and half that time-delay T is made as high-order sef-adapting filter exponent number gets final product.
Description of drawings
Fig. 1 is the structured flowchart of prior art self-adaptation first order difference microphone array system;
Fig. 2 utilizes system shown in Figure 1 to carry out the process flow diagram that voice signal is handled;
Fig. 3 is the structured flowchart of a preferred embodiment of adaptive microphone array system of the present invention;
Fig. 4 utilizes system shown in Figure 3 to carry out the process flow diagram that voice signal is handled.
Embodiment
In order to make purpose of the present invention, technical scheme and beneficial effect clearer, the present invention is described in further detail below in conjunction with drawings and Examples.
Adaptive microphone array system of the present invention and audio signal processing method thereof, upgrade control module by in microphone array system, increasing adaptive filter coefficient, whether the control adaptive filter coefficient upgrades or adaptive filter coefficient employed step value when upgrading, thereby avoided prior art self-adaptation first order difference microphone array system, the noise composition that in signal, is comprised from the rear with can compare or under the situation of phonetic element from the phonetic element in the signal in the place ahead, the efficient voice signal amplitude occurs reducing, introduce the voice distortion spinoff.
Referring to Fig. 3, Fig. 3 is the structured flowchart of a preferred embodiment of adaptive microphone array system of the present invention.As shown in Figure 3, this system comprises that the fixed directional wave beam forms module 301, sef-adapting filter 303, totalizer 305, adaptive filter coefficient renewal control module 302, time delay module 304.
Described fixed directional wave beam forms module 301 and is used for two non-directive Mikes are formed heart-shaped directive property Mike.
Adaptive microphone array system structure of the present invention and prior art system structure shown in Figure 1 difference are, system of the present invention has increased adaptive filter coefficient and has upgraded control module 302, this module forms module 301 with the fixed directional wave beam and links to each other with sef-adapting filter 303, be used to receive the fixed directional wave beam form module 301 outputs based on the signal x (k) of the place ahead incident voice signal with based on the signal n (k) of the noise signal of rear incident, and send adaptive filter coefficient according to the relative size of the noise energy of the speech energy of current time the place ahead incident and rear incident to sef-adapting filter 303 and upgrade control signal, the step value of correspondence when whether control sef-adapting filter 303 carries out coefficient update or coefficient update.
Sef-adapting filter 303, determine whether adaptive filter coefficient upgrades or step value during coefficient update according to the control signal that receives, and the usage factor update algorithm is determined update coefficients, use the residual noise signal among the signal x (k) of n (k) simulation the place ahead incident then, obtain estimated value n ' (k), and this estimated value is sent to totalizer 305.
Different with prior art system shown in Figure 1, system shown in Figure 3 also after fixed directional beam shaping module 301, has increased time delay module 304 before the totalizer 305, is used for x (k) signal is delayed time, and guarantees the causality of sef-adapting filter 303.
The time delayed signal x ' that totalizer 305 is used for comparison x (k) (k) and the estimated value n ' of the residual noise signal of the x (k) of sef-adapting filter 303 simulations (k), obtain residual signals.
Adaptive filter coefficient in the system shown in Figure 3 upgrades control module 302 can be energy comparer or sef-adapting filter step-length control module.
If it is the energy comparer that adaptive filter coefficient upgrades control module 302, then the energy comparer compares the two paths of signals x (k) of fixed directional beam shaping module 301 outputs and the energy of n (k), obtain the relative size of the two, and utilize the value generation adaptive filter coefficient of this relative size to upgrade control signal, whether the control sef-adapting filter carries out coefficient update.
If it is sef-adapting filter step-length control module that adaptive filter coefficient upgrades control module 302, then sef-adapting filter step-length control module is calculated the value of the pairing step size mu of adaptive filter coefficient renewal amount, and result of calculation sent to sef-adapting filter 303, sef-adapting filter 303 is determined the coefficient of sef-adapting filter according to this step value.
Referring to Fig. 4, Fig. 4 utilizes system shown in Figure 3 to carry out the process flow diagram that voice signal is handled.This flow process may further comprise the steps:
Concrete steps comprise: the signal f (k) that collects with Mike A306 deducts the time delayed signal b (k-d/c) of the signal b (k) that Mike B307 collects, obtains the output signal x that principal ingredient is the voice signal of the place ahead incident (k).Simultaneously, the time delayed signal f (k-d/c) with b (k) deducts f (k) obtains the output signal n that principal ingredient is the noise signal of rear incident (k), thereby forms heart-shaped directive property Mike.
If it is the energy comparer that adaptive filter coefficient upgrades control module 302, then to be obtained from the method for adaptive filter coefficient update control signal as follows for the energy comparer: at first adopt the method for single order recursion to calculate the energy envelope of x (k) and n (k), shown in formula (1) and (2)
x_env(k)＝α·x_env(k-1)+(1-α)·x
2(k) (1)
n_env(k)＝α·n_env(k-1)+(1-α)·n
2(k) (2)
In the following formula, x_env (k) is the energy envelope of signal x (k), and n_env (k) is the energy envelope of signal n (k), and α is a smoothing factor, and its span is 0＜α＜1.Formula (1) and (2) substitution formula (3) just can be compared in the hope of the energy envelope of x (k) and n (k):
The value of ratio_env (k) has reflected the relative size of the noise energy of the speech energy of current time the place ahead incident and rear incident, can utilize it to generate adaptive filter coefficient and upgrade control signal Adapt_En:
In the following formula, Thresh_ratio is a preset threshold, can be taken as 1.Following formula is a simple binary decision, can get in conjunction with formula (3), when x_env (k)＞n_env (k), ratio_env (k)＞1, be ratio_env (k)＞Thresh_ratio, Adapt_En=0 then, stop coefficient update this moment, stop the coefficient update of sef-adapting filter when promptly the signal that collects as Mike is mainly noise signal from the rear, otherwise, when x_env (k)＜n_env (k), ratio_env (k)＜1, be ratio_env (k)＜Thresh_ratio, then Adapt_En=1 carries out the coefficient update of sef-adapting filter this moment.
Compare the two paths of signals that the fixed directional wave beam forms module output by the energy comparer, whether the coefficient of control sef-adapting filter upgrades, if in the signal that Mike collects from the noise composition at rear when very little or can be with phonetic element comparable, stop to carry out coefficient update, thereby the polar mode of having avoided making microphone array system is adjusted to the dead ahead zero point, make this system the efficient voice amplitude occur reducing, introduce the spinoff of voice distortion.
Described energy comparer obtains the process of control signal Adapt_En, it is a kind of embodiment that the coefficient update of sef-adapting filter is controlled, purpose is by the control to the coefficient update of sef-adapting filter, avoids weakening the problem of input target voice signal amplitude.This embodiment also can replace with the method for controlling the sef-adapting filter step-length more flexibly, and promptly adaptive filter coefficient renewal control module 302 can be sef-adapting filter step-length control module.
Sef-adapting filter step-length control module is according to the two paths of signals x (k) and the n (k) of 301 outputs of fixed directional beam shaping module, utilize formula (3) to determine the relative size of the noise energy of the speech energy of current time the place ahead incident and rear incident, utilize the speech energy of the place ahead incident of the current time of trying to achieve to determine that with the relative size of the noise energy of rear incident the current time adaptive filter coefficient upgrades corresponding step value then, this step value is sent to sef-adapting filter as the coefficient update control signal, reach the purpose that the control adaptive filter coefficient upgrades.
Be the example explanation with NLMS adaptive filter coefficient update algorithm below.The form that the NLMS algorithm adopts in engineering practice is represented with formula (5):
Can draw sef-adapting filter by the given NLMS coefficient update formula of formula (5) in k coefficient update amount constantly is:
Obviously, adjusting step size mu can the control coefrficient renewal amount.A kind of method according to ratio_env (k) adjustment step size mu is as follows:
In the following formula, μ
RefThe reference step-length of be setting, can be in 0 to 1 scope value, the reference energy ratio of ratio_ref for setting can be taken as 1, ratio_env (k) is the x (k) that utilizes formula (3) and obtain and the energy envelope ratio of n (k).By following formula as can be known, energy envelope is bigger more than the value of ratio_env (k), and the value of step size mu is just more little, and adaptive filter coefficient updates amount σ (k) is also just more little.
The coefficient update algorithm of sef-adapting filter can be LMS, NLMS, BNLMS, RLS scheduling algorithm.In sef-adapting filter update coefficients adjustment process, if adopt different adaptive filter coefficient update algorithm, then need the data difference obtained, the process of realization is also different fully.In general, sef-adapting filter has one the tunnel to be used for simulating the input signal and one tunnel echo signal that need simulate, the i.e. reference signal of other signal.
With NLMS adaptive filter coefficient update algorithm is the example explanation, as shown in Equation (5),
Be k adaptive filter coefficient vector constantly, if the exponent number of sef-adapting filter is N, then this vector comprises N element, and when the exponent number of sef-adapting filter was single order, this vector had only an element w (k).
From formula (5) as can be seen, try to achieve
Need obtain following data: k-1 adaptive filter coefficient vector constantly
Step size mu, k-1 residual signals e_s (k-1), k-1 constantly be the reference signal vector of sef-adapting filter constantly
And k-1 reference signal constantly
Energy P
x(k-1).
Obtain the adaptive filter coefficient vector according to formula (5)
After, in conjunction with the adaptive filter coefficient vector of obtaining
Utilize the noise composition among n (k) the simulation x (k), the estimated value n ' that obtains the noise composition among the x (k) (k).Adopt the single order sef-adapting filter in the system of present embodiment, then n ' (k) equals the product of n (k) and single order adaptive filter coefficient w (k).
e_s(k)＝x′(k)-n′(k) (8)
Residual signals e_s (k) is k output signal constantly.With x (k) time-delay T is in order to guarantee the causality of sef-adapting filter, and delay time T can rule of thumb be determined by actual conditions.
Simultaneously the residual signals e_s (k) that obtains is sent into sef-adapting filter as feedback signal, be used for calculating next adaptive filter coefficient constantly according to formula (5).Next n (k+1) signal constantly is as the input signal of sef-adapting filter, sef-adapting filter is further adjusted adaptive filter coefficient according to next adaptive filter coefficient renewal control signal constantly of energy comparer or the output of sef-adapting filter step-length control module, carry out filtering repeatedly, progressively filter out the noise composition in the output signal, improve the quality of voice signal.
The fundamental starting point of using the single order sef-adapting filter in the above-described embodiments be zero point of adjusting adaptive microphone array system towards, when when zero point, orientation adjustment was to orientation, noise source place, to obtain denoising effect preferably.But when having a plurality of noise source simultaneously, this that system's 0:00 direction is pointed to the method for noise source is infeasible in theory because zero point corresponding a plurality of noise sources simultaneously.On the other hand, because exponent number is too short, the single order sef-adapting filter can't be simulated actual acoustic enviroment, its output signal n ' (k) often with x (k) in the noise composition differ greatly so poor effect of filtering and noise reduction.
The present invention adopts the single order sef-adapting filter in high-order sef-adapting filter replacement the foregoing description, and establishing high-order sef-adapting filter exponent number is N, and then the filter coefficient number is N, and filter length is N.The high-order sef-adapting filter is compared with the single order sef-adapting filter, has better filter effect, and present embodiment adopts a linear convolution process to come the noise composition of analog x ' in (k), and filter length is long more, and analog capability is strong more.Signal source n (k) obtains output signal n ' (k) through this high-order sef-adapting filter, and as shown in Equation (9), the w of the N in this formula (l) is exactly the coefficient vector of the high-order sef-adapting filter obtained according to formula (5)
N element.
The method of utilizing the high-order sef-adapting filter provided by the invention is directly pursued the signal to noise ratio (S/N ratio) maximization of output signal, makes when having a plurality of noise source, and no matter where system points to zero point, can the assurance system obtain best denoising effect.
High-order sef-adapting filter of the present invention can be higher-Order Time-Domain sef-adapting filter or high-order adaptive frequency domain filter.
In the step 404 for the causality that guarantees sef-adapting filter with x (k) time-delay T, for fear of when guaranteeing the causality of sef-adapting filter, introducing unnecessary time-delay, can adopt the linear phase sef-adapting filter, as linear phase FIR filter, in this case, time-delay T be made as sef-adapting filter exponent number N half get final product.
Adaptive filter coefficient updates is that pointwise is carried out, consider the stationarity in short-term of voice signal, in order in the robustness that guarantees algorithm, to reduce the complexity of system, the scheme of the coefficient update of above-mentioned two kinds of control sef-adapting filters can the pointwise adjustment, but adjusts once about per 10～25ms.
Sef-adapting filter among the present invention can also replace with the sub-band adaptive wave filter.When using sub-filter, if carry out coefficient update control with the energy comparer, then each subband uses independently energy comparer; If adopt the scheme of control sef-adapting filter step-length to carry out coefficient update control, then each subband independently carries out the step-length adjustment.
Adopt in the embodiments of the invention totalizer comparison output signal n ' (k) with reference signal x ' (k), in actual applications, described totalizer also can replace with other arithmetical unit, such as subtracter etc.
In a word, the above is preferred embodiment of the present invention only, is not to be used to limit protection scope of the present invention.Within the spirit and principles in the present invention all, any modification of being done, be equal to replacement, improvement etc., all should be included within protection scope of the present invention.
Claims (9)
1, a kind of adaptive microphone array system, comprise that the fixed directional wave beam forms module, sef-adapting filter, arithmetical unit, described fixed directional wave beam forms module and is used for two back-to-back non-directive Mikes are formed heart-shaped directive property Mike, it is characterized in that, this system comprises that further adaptive filter coefficient upgrades control module
Adaptive filter coefficient upgrades control module, be energy comparer or sef-adapting filter step-length control module, forming module with the fixed directional wave beam links to each other, receive the fixed directional wave beam form module output based on the signal of the place ahead incident voice signal and based on the signal of the noise signal of rear incident, and send adaptive filter coefficient according to the relative size of two-way output signal energy to sef-adapting filter and upgrade control signal, whether the control sef-adapting filter carries out the step value of coefficient update or coefficient update correspondence;
Described sef-adapting filter, upgrade the step value that control signal determines to carry out coefficient update or coefficient update correspondence according to the adaptive filter coefficient that receives, the usage factor update algorithm is determined the coefficient vector of the sef-adapting filter of current time, coefficient vector in conjunction with the sef-adapting filter of determining, the principal ingredient that forms module output with the fixed directional wave beam is the signal of the noise signal of rear incident, and the principal ingredient that simulation fixed directional wave beam forms module output is the residual noise signal in the signal of the place ahead incident voice signal;
Described arithmetical unit is used for more described principal ingredient and is the residual noise signal of this signal of the signal of the place ahead incident voice signal and simulation, obtains residual signals.
2, the system as claimed in claim 1 is characterized in that, described sef-adapting filter is the sub-band adaptive wave filter; It is one or more that described adaptive filter coefficient upgrades control module, and the number that adaptive filter coefficient upgrades control module is identical with sub band number.
3, the system as claimed in claim 1 is characterized in that, described sef-adapting filter is higher-Order Time-Domain sef-adapting filter or high-order adaptive frequency domain filter.
4, the system as claimed in claim 1, it is characterized in that, this system further comprises time delay module, this module forms module with described fixed directional wave beam and links to each other with arithmetical unit, sends to described arithmetical unit after being used for the signal that described voice signal with the place ahead incident is a principal ingredient delayed time.
5, system as claimed in claim 4 is characterized in that, when described sef-adapting filter was the linear phase sef-adapting filter, the delay time of described time delay module was half of described sef-adapting filter exponent number.
As claim 1 or 4 described systems, it is characterized in that 6, described arithmetical unit is totalizer or subtracter.
7, a kind of audio signal processing method of adaptive microphone array is characterized in that, this method may further comprise the steps:
A, utilize beam forming technique to constitute heart-shaped directive property Mike two back-to-back non-directive Mikes;
B, according to fixed directional beam shaping module output based on the signal energy of the place ahead incident voice signal and relative size, to sef-adapting filter transmission adaptive filter coefficient renewal control signal based on the signal energy of the noise signal of rear incident;
C, sef-adapting filter are according to the control signal that receives, when determining to carry out the step value of coefficient update or coefficient update correspondence, the usage factor update algorithm is determined the adaptive filter coefficient vector of current time, then in conjunction with the adaptive filter coefficient vector of determining, with the signal based on the noise signal of rear incident of fixed directional beam shaping module output, simulate based on the residual noise signal in the signal of the place ahead incident voice signal;
The residual noise signal to simulate among the signal of the place ahead incident voice signal and the step C of D, the output of contrast fixed directional beam shaping module obtains residual signals.
8, method as claimed in claim 7, it is characterized in that, the described transmission adaptive filter coefficient of step B upgrades control signal: when being mainly the noise signal of rear incident in the signal that described Mike collects, send renewal adaptive filter coefficient updates control signal to sef-adapting filter; Otherwise transmission stops to upgrade the adaptive filter coefficient updates control signal.
9, method as claimed in claim 8, it is characterized in that, the described noise signal that is mainly rear incident is determined by the ratio of the noise energy of the speech energy of the place ahead incident and rear incident, if greater than preset threshold value, then sending, the ratio of the two upgrades the adaptive filter coefficient updates control signal; Otherwise transmission stops to upgrade the adaptive filter coefficient updates control signal.
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| CN102201231B (en) * | 2010-03-23 | 2012-10-24 | 创杰科技股份有限公司 | Voice sensing method |
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