Acoustic echo canceller using multi-band nonlinear processing

1. An echo canceller, comprising:

a first multi-band filter which receives a first input audio signal and generates a first plurality of sub-band signals, each of the first plurality sub-band signals comprising a respective sub-band of the first input audio signal;

a second multi-band filter which receives a second input audio signal and generates a second plurality of sub-band signals, each of the second plurality of sub-band signals comprising a respective sub-band of the second input audio signal;

a plurality of double talk detectors, each of the double talk detectors generating a double talk flag based on at least a respective one of the first sub-band signals and a respective one of the second sub-band signals; and

a plurality of non-linear processors, each of the non-linear processors receiving at least a respective one of the double talk flags from at least one of the double talk detectors, each of the non-linear processors processing the double talk flag to select an amount of attenuation to apply to respective error signals to generate a sub-band output signal having reduced echo.

2. The echo canceller of claim 1 , further comprising:

a muti-band combiner, the muti-band combiner receiving each of the sub-band output signals and combining the respective sub-band output signals into a broadband output signal.

3. The echo canceller of claim 2 , wherein the multi-band combiner receives each of the sub-band output signals from the respective non-linear processors.

4. The echo canceller of claim 2 , further comprising:

a noise suppressor that generates a noise status indicator, the noise suppressor communicating the noise status indicator to each of the plurality of double talk detectors.

5. The echo canceller of claim 1 , further comprising:

a plurality of adaptive filters, each of the adaptive filters receiving a respective one of the double talk flags and a respective one of the second sub-band signals, and filtering the second sub-band signal in accordance with the received double talk flag.

6. The echo canceller of claim 1 , further comprising:

a plurality of adders, each of the adders receiving a respective one of the first sub-band signals and a respective one of the second sub-band signals, generating an error signal that is a difference of the first sub-band signal and the second sub-band signal, and communicating the error signal to a respective double talk detector.

7. The echo canceller of claim 6 , wherein each of the respective error signals is also communicated to a respective one of the non-linear processors.

8. The echo canceller of claim 7 , wherein each of the respective non-linear processors generates the respective sub-band output signal from the respective error signal.

9. The echo canceller of claim 6 , further comprising:

a plurality of adaptive filters, each of the adaptive filters receiving a respective one of the double talk flags and a respective one of the second sub-band signals, and filtering the second sub-band signal in accordance with the received double talk flag to generate a filtered second sub-band signal;

wherein the second sub-band signals received by the adders are filtered second sub-band signals.

10. An echo canceller, comprising:

a first multi-band filter which receives a first input audio signal and generates a first plurality of sub-band signals, each of the first plurality sub-band signals comprising a respective sub-band of the first input audio signal;

a second multi-band filter which receives a second input audio signal and generates a second plurality of sub-band signals, each of the second plurality of sub-band signals comprising a respective sub-band of the second input audio signal;

a noise suppressor that generates a noise status indicator, the noise suppressor communicating the noise status indicator to each of a plurality of double talk detectors, each of the plurality of double talk detectors generating a double talk flag based on at least a respective one of the first sub-band signals, a respective one of the second sub-band signals, and the noise status indicator; and

a plurality of non-linear processors, each of the non-linear processors receiving at least a respective one of the double talk flags from at least one of the double talk detectors, each of the non-linear processors processing the double talk flag to select an amount of attenuation to apply to respective error signals to generate a sub-band output signal having reduced echo.

11. The echo canceller of claim 10 , further comprising:

a plurality of non-linear processors, each of the non-linear processors receiving at least a respective one of the double talk flags from at least one of the double talk detectors, each of the non-linear processors processing the double talk flag to generate a sub-band output signal having reduced echo.

12. The echo canceller of claim 10 , further comprising:

a plurality of adaptive filters, each of the adaptive filters receiving a respective one of the double talk flags and a respective one of the second sub-band signals, and filtering the second sub-band signal in accordance with the received double talk flag.

13. A method of cancelling echo in a duplex communication device, comprising:

receiving a first input audio signal and generating a plurality of sub-band signals, each of the first plurality of sub-band signals comprising a respective sub-band of the first input audio signal;

receiving a second input audio signal and generating a second plurality of sub-band signals, each of the second plurality of sub-band signals comprising a respective sub-band of the second input audio signal;

generating a plurality of double talk flags, each of the double talk flags based on at least a respective one of the first sub-band signals and a respective one of the second sub-band signals; and

processing each of the double talk flags to select an amount of attenuation to apply to respective error signals to generate a respective sub-band output signal having reduced echo.

14. The method of claim 13 , further comprising:

combining the respective sub-band output signals into a broadband output signal.

15. The method of claim 13 , further comprising:

generating a noise status indicator; and

communicating the noise status indicator to each of a plurality of double talk detectors, each of which generates a respective one of the double talk flags.

16. The method of claim 13 , further comprising:

for each of the first sub-band signals, receiving a respective one of the double talk flags and a respective one of the second sub-band signals, and filtering the second sub-band signal in accordance with the received double talk flag.

17. The method of claim 13 , further comprising:

for each of the first sub-band signals and the respective second sub-band signals, generating an error signal that is a difference of the first sub-band signal and the second sub-band signal, and communicating the error signal to a respective double talk detector.

18. The method of claim 17 , further comprising:

communicating each of the error signals to a respective one of the non-linear processors.

19. The method of claim 17 , wherein processing each of the double talk flags to generate a respective sub-band output signal further comprises processing the error signal.

20. The method of claim 17 , further comprising:

for each of the first sub-band signals, receiving a respective one of the double talk flags and a respective one of the second sub-band signals, and filtering the second sub-band signal in accordance with the received double talk flag to generate a filtered second sub-band signal;

wherein generating the error signal comprises generating an error signal that is a difference of the first sub-band signal and the filtered second sub-band signal.