Bone conduction headphone speech enhancement systems and methods
Systems and methods for enhancing a headset user's own voice include at least two outside microphones, an inside microphone, audio input components operable to receive and process the microphone signals, a voice activity detector operable to detect speech presence and absence in the received and/or processed signals, and a cross-over module configured to generate an enhanced voice signal. The audio processing components includes a low frequency branch comprising low pass filter banks, a low frequency spatial filter, a low frequency spectral filter and an equalizer, and a high frequency branch comprising highpass filter banks, a high frequency spatial filter, and a high frequency spectral filter.
1. A method for enhancing a headset user's own voice comprising:
receiving a plurality of external microphone signals from a plurality of external microphones configured to sense external sounds through air conduction;
receiving an internal microphone signal from an internal microphone configured to sense a bone conduction sound from a user during speech;
processing the external microphone signals and the internal microphone signal through a lowpass process comprising:
obtaining a low frequency voice estimate and an error estimate based at least in part on filtering, by a low frequency spatial filter, a first set of signals corresponding to the external microphone signals and the internal microphone signal;
obtaining an output of a low frequency spectral filter based at least in part on filtering the low frequency voice estimate and the error estimate by the low frequency spectral filter; and
generate one or more lowpass processed signals based at least in part on the output of the low frequency spectral filter;
processing the external microphone signals, and not the internal microphone signal, through a highpass process to generate one or more highpass processed signals, the highpass process comprising filtering a second set of signals corresponding to the external microphone signals by a high frequency spatial filter and by a high frequency spectral filter; and
mixing at least one of the one or more lowpass processed signals and at least one of the one or more highpass processed signals to generate an enhanced voice signal.
2. The method of claim 1 , wherein the lowpass process further comprises lowpass filtering of the external microphone signals and the internal microphone signal.
3. The method of claim 1 , wherein the highpass process further comprises highpass filtering of the external microphone signals.
4. The method of claim 1 , wherein the filtering by the low frequency spatial filter comprises generating the low frequency voice estimate and the error estimate, and the filtering by the low frequency spectral filter comprises generating an enhanced speech signal corresponding to the output of the low frequency spectral filter.
5. The method of claim 4 , further comprising applying an equalization filter to the enhanced speech signal to mitigate distortion from the bone conduction sound.
6. The method of claim 1 , further comprising detecting voice activity in the external microphone signals and/or the internal microphone signal.
7. The method of claim 1 , wherein the filtering by the low frequency spatial filter comprises applying spatial filtering gains on the first set of signals and generating the low frequency voice estimate and the error estimate, and wherein the spatial filtering gains are adaptively computed based at least in part on a noise-suppression process.
8. The method of claim 7 , wherein the filtering by the low frequency spectral filter comprises evaluating features from the low frequency voice estimate and the error estimate, adaptively classifying the features, and computing an adaptive mask.
9. The method of claim 1 , further comprising:
receiving a speech signal, error signals, and a voice activity detection data; and
updating transfer functions if voice activity is detected.
10. The method of claim 9 , further comprising:
comparing an amplitude of a spectral output to a threshold to determine a bone conduction distortion level, and
applying voice compensation based on the comparing.
11. A system comprising:
a plurality of external microphones configured to sense external sounds through air conduction and generate external microphone signals corresponding to the sensed external sounds;
an internal microphone configured to sense a bone conduction sound from a user during speech and generate an internal microphone signal corresponding to the sensed bone conduction sound;
a lowpass processing branch configured to process the external microphone signals and the internal microphone signal through a lowpass process comprising:
obtaining a low frequency voice estimate and an error estimate based at least in part on filtering, by a low frequency spatial filter, a first set of signals corresponding to the external microphone signals and the internal microphone signal;
obtaining an output of a low frequency spectral filter based at least in part on filtering the low frequency voice estimate and the error estimate by the low frequency spectral filter; and
generating one or more lowpass processed signals based at least in part on the output of the low frequency spectral filter;
a highpass processing branch configured to process the external microphone signals, and not the internal microphone signal through a highpass process to generate one or more highpass processed signals, the highpass process comprising filtering a second set of signals corresponding to the external microphone signals by a high frequency spatial filter and by a high frequency spectral filter; and
a crossover module configured to mix at least one of the one or more lowpass processed signals and at least one of the one or more highpass processed signals to generate an enhanced voice signal.
12. The system of claim 11 , wherein the lowpass processing branch further comprises a lowpass filter bank configured to filter the external microphone signals and the internal microphone signal.
13. The system of claim 11 , wherein the highpass processing branch further comprises a highpass filter bank configured to filter the external microphone signals.
14. The system of claim 11 , wherein the lowpass processing branch further comprises the low frequency spatial filter configured to generate the low frequency voice estimate and the error estimate, and the low frequency spectral filter configured to generate an enhanced speech signal corresponding to the output of the low frequency spectral filter.
15. The system of claim 14 , further comprising an equalization filter configured to mitigate distortion from bone conduction in the enhanced speech signal.
16. The system of claim 11 , further comprising a voice activity detector configured to detect voice activity in the external microphone signals and/or the internal microphone signal.
17. The system of claim 11 , wherein the low frequency spatial filter is configured to apply spatial filtering gains on the first set of signals and generate the low frequency voice estimate and the error estimate, and wherein the spatial filtering gains are adaptively computed based at least in part on a noise-suppression process.
18. The system of claim 17 , wherein the lowpass processing branch further comprises the low frequency spectral filter configured to evaluate features from the low frequency voice estimate and the error estimate, adaptively classify the features, and compute an adaptive mask.
19. The system of claim 11 , further comprising an equalizer configured to:
receive a speech signal, error signals, and voice activity detection data; and
update transfer functions if voice activity is detected.
20. The system of claim 19 , wherein the equalizer is further configured to:
compare an amplitude of a speech signal spectral output to a threshold to determine a bone conduction distortion level, and
apply voice compensation based on the comparison.