METHOD AND DEVICE FOR SUPPRESSING RESIDUAL ECHOES

• US 20130151247A1
• Filed: 10/24/2011
• Published: 06/13/2013
• Est. Priority Date: 07/08/2011
• Status: Active Grant

• Current Assignee: Goertek Incorporated
• Original Assignee: Goertek Incorporated
• Inventors: Lou, Shasha, Li, Bo, Liu, Song
• Granted Patent: US 9,685,172 B2
• Time in Patent Office: Days
• US Class Current: 704/226
• CPC Class Codes: G10L 15/20 Speech recognition techniques specially adapted for robustness in adverse environments, e.g. in noise, of stress induced speech G10L21/02 takes precedence
• CPC Class Codes: G10L 2021/02082 the noise being echo, reverberation of the speech
• CPC Class Codes: G10L 21/0216 characterised by the method used for estimating noise
• CPC Class Codes: H04M 9/082 using echo cancellers echo cancellers per se H04B3/23
• CPC Class Codes: H04R 2201/109 Arrangements to adapt hands free headphones for use on both ears
• CPC Class Codes: H04R 2499/13 Acoustic transducers and sound field adaptation in vehicles
• CPC Class Codes: H04R 3/005 for combining the signals of two or more microphones specially adapted for hearing aids H04R25/407

Abstract

The present invention discloses a method and a device for suppressing residual echoes. The method comprises: performing adaptive filtering on M transmitter signals respectively to obtain M adaptive filtered signals; performing array-filtering on the M−1 adaptive filtered signals other than the first adaptive filtered signal to obtain M−1 array-filter output signals; subtracting each of the M−1 array-filter output signals from the first adaptive filtered signal respectively to obtain M−1 difference signals, performing time-domain/frequency-domain conversion on the M−1 difference signals respectively and selecting one of the frequency-domain signals that has the least energy; performing time-domain/frequency-domain conversion on the first adaptive filtered signal and the M^th adaptive filtered signal and then performing speech probability filtering on the converted first adaptive filtered signal and the converted M^th adaptive filtered signal to obtain one frequency-domain speech probability signal; and multiplying the frequency-domain speech probability signal with the selected signal that has the least energy, and performing frequency-domain/time-domain conversion on the multiplication result to obtain a signal as a transmitter output signal. The technical solutions of the present invention can suppress the residual echoes effectively without impairing near end speech.

Claims

1. A method for suppressing residual echoes, the method being suitable for use in a communication apparatus comprising M transmitters and one receiver, wherein M is a natural number greater than 1, and the M transmitters are arranged in line to form an array, the method comprising:

performing adaptive filtering on M transmitter signals respectively with a receiver signal to obtain M adaptive filtered signals;

processing the M−

1 adaptive filtered signals except the first adaptive filtered signal by respective array-filters to obtain M−

1 array-filter output signals, wherein for each of the adaptive filtered signals, determining weights of the array-filter that corresponds to the adaptive filtered signal according to the relative positions between the receiver and the first transmitter and the one of the transmitters that corresponds to the adaptive filtering signal;

subtracting each of the M−

1 array-filter output signals from the first adaptive filtered signal respectively to obtain M−

1 difference signals, performing time-domain/frequency-domain conversion on the M−

1 difference signals respectively and selecting one of the frequency-domain signals that has the least energy;

performing time-domain/frequency-domain conversion on the first adaptive filtered signal and the M^th adaptive filtered signal and then performing speech probability filtering on the converted first adaptive filtered signal and the converted M^th adaptive filtered signal to obtain one frequency-domain speech probability signal; and

multiplying the frequency-domain speech probability signal with the selected frequency-domain signal that has the least energy, and performing frequency-domain/time-domain conversion on the multiplication result to obtain a signal as a speech output signal in which the residual echoes have been suppressed.

2. The method of claim 1, further comprising the following step after the step of multiplying the frequency-domain speech probability signal with the selected frequency-domain signal that has the least energy:

performing spectrum filtering on the multiplication result and the receiver signal that has been subject to time-domain/frequency-domain conversion, subtracting the spectrum filtering result from the multiplication result, and performing frequency-domain/time-domain conversion on the subtraction result to obtain a signal as the speech output signal in which the residual echoes have been suppressed.

3. The method of claim 1, wherein the step of, for each of the adaptive filtered signals, determining weights of the array-filter that corresponds to the adaptive filtered signal according to the relative positions between the receiver and the first transmitter and the one of the transmitters that corresponds to the adaptive filtering signal comprises:

for each of current adaptive filtered signals among the M−

1 adaptive filtered signals except the first adaptive filtered signal, weights of the respective array-filter are determined according to the following formulas;

4. The method of claim 1, wherein the step of performing time-domain/frequency-domain conversion on the first adaptive filtered signal and the M^th adaptive filtered signal and then performing speech probability filtering on the converted first adaptive filtered signal and the converted M^th adaptive filtered signal to obtain one frequency-domain speech probability signal comprises:

calculating an arriving angle α

(f) of a sound signal arriving at the transmitter array at each frequency point according to the two results of performing time-domain/frequency-domain conversion on the first adaptive filtered signal and the M^th adaptive filtered signal; and

then calculating the speech probability pF(f) according to the following formula;

pF(f)=1−

α

(f)/90;

where pF(f) is the frequency-domain speech probability signal obtained.

5. The method of claim 2, wherein the step of performing spectrum filtering on the multiplication result and the receiver signal that has been subject to time-domain/frequency-domain conversion comprises:

dividing the full frequency range into N subbands with boundaries B₁˜

B_N+1, and performing the following calculations in each of the N subbands;

calculating a matching function H_M(f);

6. A device for suppressing residual echoes, the device being suitable for use in a communication apparatus comprising M transmitters and one receiver, wherein M is a natural number greater than 1, and the M transmitters are arranged in line to form an array, and the device comprises:

M adaptive filter components, M−

1 array-filter components, one comparison selector, one speech probability estimation component, one multiplier and one time-domain/frequency-domain converter, wherein,

the M adaptive filter components are configured to perform adaptive filtering on M transmitter signals respectively with a receiver signal to output M adaptive filtered signals;

the M−

1 array-filter components correspond to the M−

1 adaptive filtered signals except the first adaptive filtered signal in one-to-one correspondence, and each of the array-filter components comprises one array-filter, one subtractor and one time-domain/frequency-domain converter,

wherein the array-filter is configured to perform array-filtering on the corresponding adaptive filtered signal to obtain a signal and output the obtained signal to the subtractor, the subtractor is configured to subtract the signal outputted by the array-filter from the first adaptive filtered signal to obtain a signal and output the obtained signal to the time-domain/frequency-domain converter, and the time-domain/frequency-domain converter is configured to perform time-domain/frequency-domain conversion on the received signal to obtain a frequency-domain signal and output the obtained frequency-domain signal to the comparison selector;

the comparison selector is configured to receive the M−

1 frequency-domain signals outputted by the M−

1 array-filter components and select one of the frequency-domain signals that has the least energy and output the one selected signal to the multiplier;

the speech probability estimation component comprises two time-domain/frequency-domain converters and one speech probability estimator, wherein the two time-domain/frequency-domain converters are configured to perform time-domain/frequency-domain conversion on the first adaptive filtered signal and the M^th adaptive filtered signal respectively to obtain signals and output the obtained signals to the speech probability estimator, and the speech probability estimator is configured to perform speech probability filtering according to the two signals received so as to output one frequency-domain speech probability signal to the multiplier;

the multiplier is configured to multiply the two frequency-domain signals received to obtain a signal and output the obtained signal to the frequency-time/time-domain converter; and

the frequency-domain/time-domain converter is configured to perform frequency-domain/time-domain conversion on the received signal to obtain a signal as a speech output signal in which the residual echoes have been suppressed.

7. The device of claim 6, further comprising one spectrum filtering component between the multiplier and the frequency-domain/time-domain converter,

the spectrum filtering component comprises one time-domain/frequency-domain converter, one spectrum filter and one subtractor, wherein the time-domain/frequency-domain converter is configured to perform time-domain/frequency-domain conversion on the receiver signal to obtain a signal and output the obtained signal to the spectrum filter, the spectrum filter is configured to perform spectrum filtering on the signal outputted by the multiplier and the signal outputted by the time-domain/frequency-domain converter to obtain a signal and output the obtained signal to the subtractor, and the subtractor is configured to subtract the signal outputted by the spectrum filter from the signal outputted by the multiplier to obtain a signal and output the obtained signal to the frequency-domain/time-domain converter.

8. The device of claim 6, wherein weights of each of the array-filters are determined according to the following formulas:

9. The device of claim 6, wherein the speech probability estimator is configured to calculate an arriving angle α

(f) of a sound signal arriving at the transmitter array at each frequency point according to the two signals received, then calculate the speech probability pF(f) according to the following formula;

pF(f)=1−

α

(f)/90, and output pF(f) to the subtractor as the frequency-domain speech probability signal.

10. The device of claim 7, wherein the spectrum filter is configured to divide the full frequency range into N subbands having boundaries B₁˜

B_N+1, and perform the following calculations in each of the N subbands;

calculating a matching function H_M(f);