Auto-tuning of acoustic echo canceller
A gain control system for dynamically tuning an echo canceller, the echo canceller being configured to estimate an echo of a far-end signal and subtract that echo estimate from a microphone signal to output an echo cancelled signal, the gain control system comprising a monitoring unit configured to estimate an energy associated with an impulse response of an adaptive filter configured to generate the echo estimate from the far-end signal and a gain tuner configured to adjust an attenuation of at least one of the microphone signal and the far-end signal in dependence on the estimated energy.
1. A method for adjusting an attenuation of a microphone signal received by an acoustic echo canceller, the method comprising:
identifying a number of sections of the microphone signal;
for each identified section, estimating an energy associated with that section;
identifying a predetermined number, B, of the largest of the estimated energies as effective echo regions (EERs);
identifying a dominant EER from the B EERs by comparing the ratio of the energies of each the B EERs to the sum of the energies of each identified section of the microphone signal to a predefined first threshold; and
adjusting an attenuation of the microphone signal in dependence on the energy of the dominant EER.
2. The method as claimed in claim 1 , wherein the adjusting comprises comparing the energy of the dominant EER is to a second threshold and, if the energy of the dominant EER is below the second threshold, the attenuation applied to the microphone signal is decremented.
3. The method as claimed in claim 1 , wherein the adjusting comprises comparing the energy of the dominant EER to a third threshold and, if the energy of the dominant EER is above the third threshold, the attenuation applied to the microphone signal is incremented.
4. The method as claimed in claim 1 , wherein the acoustic echo canceler comprises an adaptive filter and the energy associated with each identified section is estimated by:
splitting an impulse response of the adaptive filter which corresponds to the identified section into K sub parts;
combining the energy of each of the K sub parts to form a combined energy corresponding to the identified section.
5. The method as claimed in claim 4 , wherein each of the K sub parts overlaps at least part of the preceding sub part.
6. The method as claimed in claim 4 , wherein combining the energy of each of the K sub parts comprises summing the square of the impulse responses of each K sub part.
7. The method as claimed in claim 1 , wherein identifying the B largest of the estimated energies as EERs comprises placing the estimated energies in descending order and identifying the top B values.
8. A gain control system comprising:
an energy estimator configured to identify a dominant effective echo region (EER) in a microphone signal received by an acoustic echo canceller by:
identifying a number of sections of the microphone signal,
for each identified section, estimating an energy associated with that section,
identifying a predetermined number, B, of the largest of the estimated energies as EERs, and
identifying a dominant EER from the B EERs by comparing the ratio of the energies of each the B EERs to the sum of the energies of each identified section of the microphone signal to a predefined first threshold; and
a gain tuner configured to adjust an attenuation of the microphone signal in dependence on the energy of the dominant EER.
9. The gain control system as claimed in claim 8 , wherein the gain tuner is further configured to adjust the attenuation by comparing the energy of the dominant EER is to a second threshold and, if the energy of the dominant EER is below the second threshold, the attenuation applied to the microphone signal is decremented.
10. The gain control system as claimed in claim 8 , wherein the gain tuner is further configured to adjust the attenuation by the adjusting comprises comparing the energy of the dominant EER to a third threshold and, if the energy of the dominant EER is above the third threshold, the attenuation applied to the microphone signal is incremented.
11. The gain control system as claimed in claim 8 , wherein the energy estimator is further configured to estimate the energy associated with each identified section by:
splitting an impulse response of an adaptive filter which corresponds to the identified section into K sub parts;
combining the energy of each of the K sub parts to form a combined energy corresponding to the identified section.
12. The gain control system as claimed in claim 11 , wherein each of the K sub parts overlaps at least part of the preceding sub part.
13. The gain control system as claimed in claim 11 , wherein the energy estimator is further configured to combine the energy of each of each of the K sub parts by summing the square of the impulse responses of each K sub part.
14. The gain control system as claimed in claim 8 , wherein the energy estimator is further configured to identify the B largest of the estimated energies as EERs by placing the estimated energies in descending order and identifying the top B values.
15. A non-transitory machine readable storage medium having stored thereon processor executable instructions that when executed cause at least one processor to implement a method for adjusting an attenuation of a microphone signal received by an acoustic echo canceller, the method comprising:
identifying a number of sections of the microphone signal;
for each identified section, estimating an energy associated with that section;
identifying a predetermined number, B, of the largest of the estimated energies as effective echo regions, EERs;
identifying a dominant EER from the B EERs by comparing the ratio of the energies of each the B EERs to the sum of the energies of each identified section of the microphone signal to a predefined first threshold; and
adjusting an attenuation of the microphone signal in dependence on the energy of the dominant EER.