CN101662714B - Microphone array designing method for locating pickup in complex sound field based on time reversal - Google Patents

Abstract

The invention discloses a microphone array designing method for locating pickup in a complex sound field, comprising the steps: (1) distributing microphone array in any one of horizontal planes, appointing a preset object point, and measuring the impulse response of each channel; and (2) in the process of pickup, convoluting signals collected by each channel and the corresponding impulse responseafter the time reversal and overlapping to obtain a final signal. The method can pick up a sound source signal of an appointed point in the complex sound field, can distinguish the signals with different distances at the same direction, and has a greater practical value.

Description

Microphone array designing method for locating pickup in complex sound field based on time reversal

One, technical field

The present invention relates to the design of locating pickup microphone array, relating in particular to is the microphone array that the near field sound-source signal in complex sound field picks up.

Two, background technology

The main application scenario of microphone array pick up has: consumer electronics product of stage, large conference room, news spot, video conferencing, voice-enabled chat, speech coding, speech recognition and completion voice communication or the like.Traditional wave beam formation method hypothesis sound source is in the far-field region of array, and only is directed against the signal of distinguishing from different directions.And beam-forming technology and adaptive beam that existing near field pick up technology mainly is divided into data independence form technology; These methods are mostly derived from the basis of original far field beam-forming technology; Therefore same to limited in one's ability from the signal resolution of same direction different distance, and the pick up of shorter mention complex sound field.Existing near field pickup technology can only be picked up effectively to the different directions sound source, can't distinguish for the signal of same direction different distance, can not pick up the signal of near field assigned address, can not pick up the signal in the complex sound field.

The open CN101297587 of Chinese patent, CN101076203, CN1645971 are that the pick up that contains microphone array is sent out the meter method.The method for designing that CN101076203 provides is to adopt the circular arc array, uses its natural focusing, and the signal that circle centre position is collected directly carries out addition and obtains the result.In free found field, it has good effect, and simple and practical, but for complex sound field, its performance can descend, and is no longer practical.The sound pick up equipment of CN101297587 has only been considered the influence of direct sound wave, does not consider for influences such as the reflection of being drawn by complex sound field, refractions.Influences such as the reflection that CN1645971 does not have to consider to be drawn by complex sound field equally, refraction, the detection and localization that contains in the simultaneity factor is only effective to certain objects, and has strengthened the device complexity.French scholars in 1991 propose the notion (C.Prada of time reversal first; F.Wu; M.Fink, " The iterative time reversalmirror:A solution to self-focusing in the pulse echo mode, " J.Acoust.Soc.Am.90 (2); Pp.1119～1129, Aug.1991).After this be used for fields such as ultrasonic, image, communication about the processing of time reversal more.Its common description is that the signal that receives is inverted end to end, returns along former road again, and process is time reversal.Its essence is the space-time matched filter of the transfer function between Applying Array and the impact point.Do not see as yet at present for the beam-forming technology of data independence, the array locating pickup report of the application time reversal in complex sound field.

Three, summary of the invention

1, goal of the invention: can't distinguish signal from same direction different distance to current relevant beam-forming technology; Can't pick up the signal of required near field position; Can't pick up the shortcoming of the signal in the complex sound field, the object of the present invention is to provide a kind of method for designing of microphone array that can locating pickup in complex sound field.This array can be distinguished the signal of same direction different distance, and can in complex sound field, pick up the signal of desired location.

2, technical scheme: for realizing the foregoing invention purpose, the method for designing of locating pickup in complex sound field microphone array of the present invention is based on time reversal principle, and this method may further comprise the steps:

(1), specify predetermined target point, measure or calculate the impulse response of each passage.

(2), to the time reversal to impulse response recited above, impulse response digitlization this moment is carried out backward with this Serial No., has promptly accomplished time reversal and preserves.

(3), the signal and the impulse response signals of respective channel after time reversal of each passage collection are carried out convolution, at last the signal of all passages is carried out addition and become array output signal.

The flow chart of entire method is seen accompanying drawing 1.

3, beneficial effect: the present invention compared with prior art; Its remarkable advantage is to be: (1) is not only in free space; Even in complex sound field, also good pickup effect can be arranged; For example, be the circular arc array of 0.37m for radius, it picks up more than the big 5dB of signal of the signal at predetermined target point place than other place (about 25cm is far away for the preset distance impact point).(2) to lay form simple for microphone array, places to fix arbitrarily to get final product.(3) can distinguish signal from same direction different distance.(4) weight vector is fixed, and robustness is good.

Four, description of drawings

Fig. 1 is the flow chart of entire method.

Fig. 2 is that array microphone of the present invention (is example with circular arc) is placed sketch map.

Impulse response in the anechoic chamber of Fig. 3 actual measurement.

Fig. 4 is that theory compares with measured value in anechoic chamber.Among the figure pick-up capability of the diverse location distribution map after to center of circle normalization, the dB of unit

Fig. 5 compares at the measured value of normal room and reverberation room and the theoretical value in the free space.Among the figure pick-up capability of the diverse location distribution map after to center of circle normalization, the dB of unit

Five, embodiment

With 15 passage microphone circular arc arrays, radius is 0.37m below, and every channel sample rate is 15kHz, and the center of circle is a predetermined target point, and signal frequency is that 1kHz elaborates to the present invention.

1, in horizontal plane, place the semicircle array of microphone arbitrarily, the array radius is 0.37m, and array contains 15 microphones, and equal angles is spaced apart.Schematic configuration view is seen Fig. 2.

2, place loud speaker at the predetermined target point place, the linear signal frequently of emission, its frequency range is 200Hz～7200Hz, tries to achieve impulse response through the Wiener filtering method, the Wiener filtering method asks the impulse response introduction following:

$H\left(\mathrm{\ω}\right)=\frac{X\left(\mathrm{\ω}\right)Y^{*}\left(\mathrm{\ω}\right)}{{\left|X\left(\mathrm{\ω}\right)\right|}^2+q}$

Wherein, X (ω) is the Fourier transform that transmits, and transmits to be the linear frequency sweep signal, and frequency range is 200Hz～7200Hz.Y (ω) receives signal and transmits the maintenance synchronism for receiving the Fourier transform of signal.H (ω) is the Fourier transform of impulse response.Q is a noise power spectral density and the ratio of signal power spectrum density, generally is taken as definite value, and size is worth more for a short time about 0～1, shows that noise is more little, has got 1/20 here.At last H (ω) is done the impulse response that inversefouriertransform obtains time domain.The impulse response that Fig. 3 records for anechoic chamber.

3, along Fig. 1 (a) x direction of principal axis, move audio amplifier, position, every arrangement one place, the signal of emission 1kHz, the impulse response of the signal of each passage collection and corresponding elapsed time counter-rotating carry out after the convolution again that stack obtains final signal.Its final effect figure sees Fig. 4,5.

Interpretation of result:

Adopt provided by the invention in complex sound field the method for locating pickup array design; Experiment shows that with notional result pickup effect is preferably arranged; For radius is the circular arc array of 0.37m, and it picks up more than the big 5dB of signal of the signal at predetermined target point place than other place (about 25cm is far away for the preset distance impact point).Therefore adopt method provided by the invention to be implemented in that locating pickup is fully feasible in the complex sound field.

Claims (5)

1. microphone array designing method for locating pickup in complex sound field is characterized in that: based on technology time reversal, may further comprise the steps:

(1) in the space, places microphone array in the arbitrary plane, specify predetermined target point;

(2) record the impulse response of each passage;

(3) impulse response in the step (2) is carried out time reversal;

(4) signal of each passage collection carries out convolution with the middle corresponding signal of step (3), stack obtains the output signal of array again.

2. microphone array designing method for locating pickup in complex sound field as claimed in claim 1; It is characterized in that; Microphone array in the step (1) is the array of semicircle, linearity or other shape in the space, laying in the arbitrary plane, and array is made up of microphone unit; For predetermined target point; Semicircle array selects its circle centre position; The predetermined target point of linear array is selected on its perpendicular bisector; Distance from array is half place of array length, and the selection principle of the predetermined target point of other array of shapes is to be taken at its center, and the distance that leaves nearest microphone is half place of array radius.

3. microphone array designing method for locating pickup in complex sound field as claimed in claim 1 is characterized in that, the impulse response in the step (2) calculates through the Wiener filtering method.

4. microphone array designing method for locating pickup in complex sound field as claimed in claim 1; It is characterized in that; Step (3) is carried out time reversal to the impulse response in the step (2); The impulse response that calculates through the Wiener filtering method is the string number sequence, this sequence is carried out backward promptly accomplished time reversal.

5. microphone array designing method for locating pickup in complex sound field as claimed in claim 1; It is characterized in that; Step (4) is carried out convolution with the signal and the impulse response signals of respective channel after time reversal of each passage collection, at last the signal of all passages is carried out addition and becomes array output signal.

Images