Method of compensating a processed audio signal
A method comprising: at an electronic device ( 100 ) having an array microphones ( 101 ) with a plurality of microphones and a processor ( 102 ): receiving a plurality of microphone signals (x 1 , x 2 , x 3 ) from the plurality of microphones; generating a processed signal (XP) from the plurality of microphone signals using one or both of beamforming and deconvolution; generating a compensated processed signal (XO) by compensating the processed audio signal (XP) in accordance with compensation coefficients (Z). Generating the compensated processed signal comprises: generating first spectrum values (PXP) from the processed audio signal; generating reference spectrum values (<PX>) from multiple second spectrum values (PX 1 , PX 2 , PX 3 ) generated from each of at least two of the microphone signals in the plurality of microphone signals (x 1 , x 2 , x 3 ); and generating the compensation coefficients (Z) from the reference spectrum values (<PX>) and the first spectrum values (PXP). The compensation may improve undesired effects related to e.g. coloration at the output of multi-microphone systems involving e.g. one or both of beamforming and deconvolution of microphone signals from a microphone array.
1. A method comprising, at an electronic device having an array of microphones and a processor:
receiving a plurality of microphone signals from the array of microphones;
generating a processed audio signal from the plurality of microphone signals;
compensating for coloration in the processed audio signal in accordance with a plurality of compensation coefficients by frequency response equalizing the processed audio signal, comprising:
generating first spectrum values from the processed audio signal;
generating multiple second spectrum values from each of at least two but less than a full value of the plurality of microphone signals;
generating reference spectrum values from the multiple second spectrum values; and
generating the plurality of compensation coefficients from the reference spectrum values and the first spectrum values,
wherein the the compensating reduces a predefined difference measure between a predefined norm of spectrum values of the compensated processed audio signal and the reference spectrum values.
2. A method according to claim 1 ,
wherein the multiple second spectrum values are each represented in an array of values; and
wherein the reference spectrum values are generated by computing an average or a median value across, respectively, at least two or at least three of the multiple second spectrum values.
3. A method according to claim 1 , wherein the compensating includes noise reduction.
4. A method according to claim 3 , wherein the generating of a processed audio signal from the plurality of microphone signals includes one or more of spatial filtering, beamforming, and deconvolution.
5. A method according to claim 4 ,
wherein the first spectrum values and the reference spectrum values are computed for respective elements in an array of elements; and
wherein the compensation coefficients are computed, per corresponding respective element, in accordance with a ratio between a value of the reference spectrum values and a value of the first spectrum values.
6. A method according to claim 5 ,
wherein values of the processed audio signal and the compensation coefficients are computed for respective elements in an array of elements; and
wherein the values of the compensated processed audio signal are computed, per corresponding respective elements, in accordance with a multiplication of the values of the processed audio signal and the compensation coefficients.
7. A method according to claim 6 , wherein the generating reference spectrum values is in accordance with a second temporal average over reference spectrum values, and/or the multiple second spectrum values are in accordance with a third temporal average over respective multiple second spectrum values.
8. A method according to claim 6 , wherein the generating first spectrum values is in accordance with a first temporal average over first spectrum values.
9. A method according to claim 8 , wherein:
the first temporal average and the second temporal average are in accordance with mutually corresponding averaging properties; and/or
the first temporal average and the third temporal average are in accordance with mutually corresponding averaging properties.
10. A method according to claim 9 , wherein the first spectrum values, the multiple second spectrum values, and the reference spectrum values are computed for consecutive frames of microphone signals.
11. A method according to claim 10 , wherein the electronic device comprises a circuit configured to reproduce a far-end audio signal via a loudspeaker, the method comprising:
determining that the far-end audio signal meets a first criterion and/or fails to meet a second criterion, and in accordance therewith forgo one or more of:
compensating for coloration in the processed audio signal,
generating first spectrum values from the processed audio signal, and generating reference spectrum values from multiple second spectrum values; and
determining that the far-end audio signal fails to meet the first criterion and/or meets the second criterion, and in accordance therewith:
performing one or more of:
compensating for coloration in the processed audio signal,
generating first spectrum values from the processed audio signal, and
generating reference spectrum values from multiple second spectrum values.
12. A method according to claim 11 , wherein the first spectrum values and the reference spectrum values are computed in accordance with a predefined norm, selected from the group of: the 1-norm, the 2-norm, the 3-norm, a logarithmic norm or another predefined norm.
13. A method according to claim 12 , wherein the generating of a processed audio signal from the plurality of microphone signals is performed at a first semiconductor portion receiving the plurality of respective microphone signals in a time-domain representation and outputting the processed audio signal in a time-domain representation; and
at a second semiconductor portion:
the first spectrum values are computed from the processed audio signal by a time-domain-to-frequency-domain transformation of the microphone signals; and
the multiple second spectrum values are computed by a respective time-domain-to-frequency-domain transformation of the respective microphone signals.
14. A method according to claim 13 , further comprising:
communicating, in real-time, the compensated processed audio signal to one or more of a loudspeaker of the electronic device, a receiving device in proximity of the electronic device, and a far-end receiving device.
15. A method according to claim 8 , wherein, further, the generating reference spectrum values is in accordance with a second temporal average over reference spectrum values, and/or the multiple second spectrum values are in accordance with a third temporal average over respective multiple second spectrum values.
16. An electronic device, comprising:
an array of microphones with a plurality of microphones; and
one or more signal processors, wherein the one or more signal processors are configured to perform any of the method of claim 1 .
17. An electronic device according to claim 16 , configured as a speakerphone or a headset or a hearing instrument.