Methods and devices for reverberation suppression

1. A method for reverberation suppression in an audio device comprising:

determining a first estimated reverberation component of a reverberant speech signal that is measured by at least one microphone of the audio device;

generating a first de-reverberated output signal with a first reverberation suppression based on the reverberant speech signal and the first estimated reverberation component that is based on a first synthetic impulse response;

generating a second improved reverberation component using the entire first de-reverberated output signal as an input of a second synthetic impulse response; and

generating a second de-reverberated output signal with a second reverberation suppression based on the reverberant speech signal and the second improved reverberation component.

2. The method of claim 1 , wherein the first estimated reverberation component is based on a convolution of the reverberant speech signal and a second portion of the first synthetic impulse response without being based on a first portion of the first synthetic impulse response.

3. The method of claim 2 , wherein the first estimated reverberation component and the second improved reverberation component are based on a reverberation time T 60 that is defined as a time for energy in a reverberant room to decay by 60 dB.

4. The method of claim 3 , wherein the reverberation time T 60 is a frequency dependent term that adjusts an exponential decay as a function of frequency.

5. The method of claim 3 , wherein the second improved reverberation component is based on a convolution of the first de-reverberated output signal and a second portion of the second synthetic impulse response without being based on a first portion of the second synthetic impulse response.

6. The method of claim 5 , wherein the first synthetic impulse response is time delayed in comparison to the second synthetic impulse response.

7. The method of claim 1 , further comprising:

generating a third improved reverberation component using the second de-reverberated output signal; and

generating a third de-reverberated output signal with a third reverberation suppression based on the reverberant speech signal and the third improved reverberation component.

8. An audio device comprising:

at least one microphone for measuring a reverberant speech signal; and

audio signal processing circuitry coupled to the microphone, the audio signal processing circuitry to determine a first estimated reverberation component of the reverberant speech signal that is received by the microphone, to generate a first de-reverberated output signal with a first reverberation suppression based on the reverberant speech signal and the first estimated reverberation component that is based on a first synthetic impulse response, to generate a second improved reverberation component using the entire first de-reverberated output signal as an input of a second synthetic impulse response, and to generate a second de-reverberated output signal with a second reverberation suppression based on the reverberant speech signal and the second improved reverberation component.

9. The audio device of claim 8 , wherein the first estimated reverberation component is based on a convolution of the reverberant speech signal and a second portion of the first synthetic impulse response without being based on a first portion of the first synthetic impulse response.

10. The audio device of claim 9 , wherein the first and second reverberation components are based on a reverberation time T 60 that is defined as a time for energy in a reverberant room to decay by 60 dB.

11. The audio device of claim 10 , wherein the reverberation time T 60 is a frequency dependent term that adjusts an exponential decay as a function of frequency.

12. The audio device of claim 9 , wherein the second improved reverberation component is based on a convolution of the first de-reverberated output signal and a second portion of the second synthetic impulse response.

13. The audio device of claim 12 , wherein the first synthetic impulse response is time delayed in comparison to the second synthetic impulse response.

14. The audio device of claim 8 , wherein the audio signal circuitry to generate a third improved reverberation component using the second de-reverberated output signal and to generate a third de-reverberated output signal with a third reverberation suppression based on the reverberant speech signal and the third improved reverberation component.

15. An apparatus comprising:

a means for measuring a reverberant speech signal; and

a means for audio signal processing to determine a first estimated reverberation component of the reverberant speech signal that is received by a microphone, to generate a first de-reverberated output signal with a first reverberation suppression based on the reverberant speech signal and the first estimated reverberation component that is based on a first synthetic impulse response, to generate a second improved reverberation component using the entire first de-reverberated output signal as an input of a second synthetic impulse response, and to generate a second de-reverberated output signal with a second reverberation suppression based on the reverberant speech signal and the second improved reverberation component.

16. The apparatus of claim 15 , wherein the first estimated reverberation component is based on a convolution of the reverberant speech signal and a second portion of the first synthetic impulse response without being based on a first portion of the first synthetic impulse response.

17. The apparatus of claim 16 , wherein the first and second reverberation components are based on a reverberation time T 60 time, which is a frequency dependent term that adjusts an exponential decay as a function of frequency.

18. The apparatus of claim 17 , wherein the second improved reverberation component is based on a convolution of the first de-reverberated output signal and a second portion of the second synthetic impulse response.

19. The apparatus of claim 18 , wherein the first synthetic impulse response is time delayed in comparison to the second synthetic impulse response.

20. A method for reverberation suppression with an audio device comprising:

determining an estimated reverberation component of a reverberant speech signal that is measured by at least one microphone of the audio device; and

generating a de-reverberated output signal with a reverberation suppression based on the reverberant speech signal and the estimated reverberation component, wherein the estimated reverberation component is based on the reverberant speech signal and a second reverberant portion of a synthetic impulse response without being based on a first direct portion of the synthetic impulse response.

21. The method of claim 20 , wherein the estimated reverberation component is computed by determining a convolution of the reverberant speech signal and the second reverberant portion of the synthetic impulse response.

22. The method of claim 21 , wherein the estimated reverberation component is determined in a time domain, wherein the synthetic impulse response is based on a reverberation time T 60 that is defined as a time for energy in a reverberant room to decay by 60 dB, wherein the reverberation time T 60 is a frequency dependent term that adjusts an exponential decay as a function of frequency.

23. The method of claim 21 , wherein the synthetic impulse response depends upon frequency with reverberation decreasing for higher frequencies.

24. The method of claim 20 , wherein the reverberant speech signal includes a first portion that corresponds to a direct path from a user to the microphone and a second portion that corresponds to other paths from the user to the microphone based on reflections from walls, a ceiling, a floor, or other objects.