Audio processing compression system using level-dependent channels
View Patent ↗Disclosed herein, among other things, are methods and apparatus for a level-dependent compression system for hearing assistance devices, such as hearing aids. The present subject matter includes a hearing assistance device having a buffer for receiving time domain input signals and a frequency analysis module to convert time domain input signals into a plurality of subband signals. A power detector is adapted to receive the subband signals and to provide a subband version of the input signals. A nonlinear gain stage applies gain to the plurality of subband versions of the input signals, and a frequency synthesis module processes subband signals from the nonlinear gain stage and to create a processed output signal. The device also includes a filter for filtering the signals, and a level-dependent compression module. The level-dependent compression module is adapted to provide bandwidth control to the plurality of subband signals produced by the frequency analysis stage.
1. A method of operating a hearing assistance device, the method comprising:
receiving time-domain input signals;
converting received time domain input signals into a plurality of subband signals;
processing the plurality of subband signals to:
apply nonlinear gain to the plurality of subband signals; and
adjust width of subbands based on detected power as a function of frequency using a level-dependent compression module adapted to provide bandwidth control to the plurality of subband signals; and
converting the processed plurality of subband signals to time domain signals.
2. The method of claim 1 , wherein the level-dependent compression module includes level-dependent analysis channels to control a compressive-gain signal as a function of frequency.
3. The method of claim 2 , wherein the level-dependent analysis channels include channels with level-dependent bandwidths.
4. The method of claim 1 , wherein power from bands of a static bandwidth are weighted and summed according to signal level.
5. The method of claim 1 , wherein the level-dependent compression module includes uniformly scaled analysis filterbanks.
6. The method of claim 1 , wherein the level-dependent compression module includes non-uniformly scaled analysis filterbanks.
7. The method of claim 1 , wherein the level-dependent compression module is adapted for compression of audio signals.
8. The method of claim 7 , wherein the audio signals include speech.
9. The method of claim 7 , wherein the audio signals include music.
10. A method of operating a hearing assistance device, the method comprising:
converting time domain input signals into a plurality of subband signals;
processing the plurality of subband signals, including:
applying nonlinear gain to the plurality of subband versions of the input signals; and
adding a weighted power of a subband signal to at least one other weighted subband signal in an adjacent subband using a level-dependent compression module to provide a final instantaneous-power estimate, and converting the processed plurality of subband signals to time domain signals; and
filtering the time domain signals using a filter.
11. The method of claim 10 , wherein the level-dependent compression module is adapted to provide a final instantaneous power estimate for power integration.
12. The method of claim 10 , wherein the level-dependent compression module is adapted to provide a final instantaneous power estimate for nonlinear gain.
13. The method of claim 10 , wherein the level-dependent compression module is adapted to provide a final instantaneous power estimate for frequency synthesis.
14. The method of claim 10 , wherein the level-dependent compression module is adapted to provide a final instantaneous power estimate for time-domain filtering.
15. The method of claim 10 , wherein the filter includes a finite impulse response (FIR) filter.
16. The method of claim 10 , wherein the weighted power is determined using weights as a function of target bandwidth.
17. The method of claim 16 , wherein the weights are symmetrically distributed across adjacent bands.
18. The method of claim 16 , wherein the weights are asymmetrically distributed across adjacent bands.
19. The method of claim 10 , wherein the level-dependent compression module includes an unbranched architecture.
20. The method of claim 10 , wherein the level-dependent compression module includes a side-branched architecture.