Acoustic fence
For online audio/video conferencing applications deployed in an open office environment, using shared conference devices, it can be advantageous to define an acoustic fence. A non-participant audio received from outside the acoustic fence can be considered noise and filtered out before transmission of an audio signal to a far end recipient. Three suppression stages are used to filter the non-participant audio. The first suppression stage uses beamformers for suppression. The second suppression stage is mask-based, and the third suppression stage is reference-based. The three suppression stages filter out non-participant audio signals, having a wide range of frequencies.
1. A method comprising:
receiving a plurality of audio signals through a multi-channel audio input device;
receiving parameters of an acoustic fence, the parameters comprising an angle or a distance for the acoustic fence;
applying a first suppression stage to the audio signals to generate a first suppression stage output, applying the first suppression stage comprising suppressing audio signals outside the acoustic fence to generate an in-beam signal and suppressing audio signals inside the acoustic fence to generate a reference signal;
applying a second suppression stage to the first suppression stage output to generate a second suppression stage output signal, applying the second suppression stage comprising generating a suppression mask, the suppression mask configured to suppress the audio signals outside the acoustic fence; and
applying a third suppression stage comprising applying a combined suppression mask and a reference-based mask to the second suppression stage output signal, and
generating a final output signal, wherein the reference-based mask suppresses residual low frequency components of audio signals outside the acoustic fence after processing by first and second suppression stages.
2. The method of claim 1 , wherein applying the first suppression to the audio signals comprises:
generating an in-beam beamformer comprising audio signals outside the acoustic fence suppressed; and
generating an out-beam beamformer comprising the reference signal by suppressing audio signals inside the acoustic fence.
3. The method of claim 1 , wherein applying the second suppression and generating the suppression mask comprises:
performing feature extraction, wherein the features comprise angle and/or distance of a source of an audio signal relative to the multi-channel audio input device; and
generating the suppression mask based on the received parameters of the acoustic fence.
4. The method of claim 1 , wherein applying the third suppression comprises:
receiving, by the third suppression stage, the suppression mask generated by the second suppression stage;
generating, by the third suppression stage, the reference-based mask comprising multipliers to suppress low frequency residual components of signals outside the acoustic fence; and
combining the suppression mask and the reference-based mask.
5. The method of claim 1 , wherein the first suppression comprises two time-domain filter and sum beamformers, wherein the first suppression comprises generating in-beam and out-beam beamformers, wherein the in-beam and out-beam are inverse of one another.
6. The method of claim 1 , wherein generating the suppression mask is based on determining an angle and/or distance of a source of an audio signal relative to the multi-channel audio input device.
7. The method of claim 1 , wherein generating the suppression mask comprises:
applying a direction of arrival (DOA) technique to determine an angle of a source of an audio signal relative to the multi-channel audio input device; and
applying a generalized cross correlation with phase transform (GCC-PHAT) or Steered-Response Power Phase Transform (SRP-PHAT) based localization technique to determine the distance of a source of an audio signal relative to the multi-channel audio input device.
8. A non-transitory computer storage medium comprising processor-executable program instructions configured to cause one or more processors to:
receive a plurality of audio signals through a multi-channel audio input device;
receive parameters of an acoustic fence, the parameters comprising an angle or a distance for the acoustic fence;
apply a first suppression stage to the audio signals to generate a first suppression stage output, applying the first suppression stage comprising suppressing audio signals outside the acoustic fence to generate an in-beam signal and suppressing audio signals inside the acoustic fence to generate a reference signal;
apply a second suppression stage to the first suppression stage output to generate a second suppression stage output signal, applying the second suppression stage comprising generating a suppression mask, the suppression mask configured to suppress the audio signals outside the acoustic fence; and
apply a third suppression stage comprising applying a combined suppression mask and a reference-based mask to the second suppression stage output signal, and
generate a final output signal, wherein the reference-based mask suppresses residual low frequency components of audio signals outside the acoustic fence after processing by first and second suppression stages.
9. The non-transitory computer storage of claim 8 , further comprising processor-executable program instructions configured to cause the one or more processors to:
generate an in-beam beamformer comprising audio signals outside the acoustic fence suppressed; and
generate an out-beam beamformer comprising the reference signal by suppressing audio signals inside the acoustic fence.
10. The non-transitory computer storage of claim 8 , wherein applying the second suppression and generating the suppression mask comprises:
perform feature extraction, wherein the features comprise angle and distance of a source of an audio signal relative to the multi-channel audio input device; and
generate the suppression mask based on the received parameters of the acoustic fence.
11. The non-transitory computer storage of claim 8 , further comprising processor-executable program instructions configured to cause the one or more processors to:
receive, by the third suppression stage, the suppression mask generated by the second suppression stage;
generate, by the third suppression stage, the reference-based mask comprising multipliers to suppress low frequency residual components of signals outside the acoustic fence; and
combine the suppression mask and the reference-based mask.
12. The non-transitory computer storage of claim 8 , wherein the first suppression comprises two time-domain filter and sum beamformers, wherein the first suppression comprises generating in-beam and out-beam beamformers, wherein the in-beam and out-beam are inverse of one another.
13. The non-transitory computer storage of claim 8 , wherein generating the suppression mask is based on determining an angle and distance of a source of an audio signal relative to the multi-channel audio input device.
14. The non-transitory computer storage of claim 8 , further comprising processor-executable program instructions configured to cause the one or more processors to:
apply a direction of arrival (DOA) technique to determine an angle of a source of an audio signal relative to the multi-channel audio input device; and
apply a generalized cross correlation with phase transform (GCC-PHAT) or Steered-Response Power Phase Transform (SRP-PHAT) based localization technique to determine the distance of a source of an audio signal relative to the multi-channel audio input device.
15. A system comprising:
a non-transitory computer-readable medium; and
one or more processors communicatively coupled to the non-transitory computer-readable medium, the one or more processors configured to execute processor-executable program instructions stored in the non-transitory computer-readable medium to:
receive a plurality of audio signals through a multi-channel audio input device;
receive parameters of an acoustic fence, the parameters comprising an angle or a distance for the acoustic fence;
apply a first suppression stage to the audio signals to generate a first suppression stage output, applying the first suppression stage comprising suppressing audio signals outside the acoustic fence to generate an in-beam signal and suppressing audio signals inside the acoustic fence to generate a reference signal;
apply a second suppression stage to the first suppression stage output to generate a second suppression stage output signal, applying the second suppression stage comprising generating a suppression mask, the suppression mask configured to the suppress the audio signals outside the acoustic fence; and
apply a third suppression stage comprising applying a combined suppression mask and a reference-based mask to the second suppression stage output signal, and
generate a final output signal, wherein the reference-based mask suppresses residual low frequency components of audio signals outside the acoustic fence after processing by first and second suppression stages.
16. The system of claim 15 , wherein the one or more processors are configured to execute further processor-executable program instructions stored in the non-transitory computer-readable medium to:
generate an in-beam beamformer comprising audio signals outside the acoustic fence suppressed; and
generate an out-beam beamformer comprising the reference signal by suppressing audio signals inside the acoustic fence.
17. The system of claim 15 , wherein the one or more processors are configured to execute further processor-executable program instructions stored in the non-transitory computer-readable medium to:
perform feature extraction, wherein the features comprise angle and/or distance of a source of an audio signal relative to the multi-channel audio input device; and
generate the suppression mask based on the received parameters of the acoustic fence.
18. The system of claim 15 , wherein the one or more processors are configured to execute further processor-executable program instructions stored in the non-transitory computer-readable medium to:
receive, by the third suppression stage, the suppression mask generated by the second suppression stage;
generate, by the third suppression stage, the reference-based mask comprising multipliers to suppress low frequency residual components of signals outside the acoustic fence; and
combine the suppression mask and the reference-based mask.
19. The system of claim 15 , wherein the first suppression comprises two time-domain filter and sum beamformers, wherein the first suppression comprises generating in-beam and out-beam beamformers, wherein the in-beam and out-beam are inverse of one another.
20. The system of claim 15 , wherein generating the suppression mask is based on determining an angle and/or distance of a source of an audio signal relative to the multi-channel audio input device.