Methods and apparatus for adapting speech coders to improve cochlear implant performance
View Patent ↗Cochlear implant performance is improved by extracting pitch information and encoding such pitch information into the processor of a cochlear implant. One embodiment of the invention is to explicitly extract the pitch and deliver it to the cochlear implant by co-varying the stimulated site and rate. Another embodiment of the invention is to implicitly encode the pitch information via a code book that serves as the carrier of stimulation in the cochlear implant.
1. A method for improving sound processing by a cochlear implant comprising the acts of:
receiving sound containing a voiced component;
extracting pitch information from said sound for the voiced component; and
adding said pitch information into a continuous-interleaved-stimulation (CIS) processor of the cochlear implant, wherein a stimulation rate and position is covaried to encode the pitch information.
2. The method of claim 1 , wherein extracting pitch information comprises extracting pitch information using one of time-domain processing and spectral-domain processing.
3. The method of claim 1 , further comprising extracting a slowly-varying frequency modulation (FM) signal from said sound.
4. The method of claim 3 , wherein extracting the slow-varying FM signal comprises extracting the slow-varying FM signal using a phase vocoder, and wherein the slow-varying FM signal is extracted around a center frequency of an analysis filter of the phase vocoder.
5. The method of claim 3 , further comprising adding the slow-varying FM signal into the CIS processor.
6. The method of claim 3 , further comprising adapting a code-excited linear predictive (CELP) vocoder using the slow-varying FM signal.
7. The method of claim 6 , wherein the CELP vocoder comprises a codebook containing distinguishable temporal patterns, and wherein said code book is available to the CIS processor.
8. The method of claim 7 , further comprising storing the codebook in an implantable part of the cochlear implant.
9. The method of claim 1 , wherein adding the pitch information comprises mapping the pitch information to a set of basal electrodes of the cochlear implant.
10. The method of claim 9 , further comprising mapping temporal envelopes to a set of apical electrodes of the cochlear implant.
11. The method of claim 1 , further comprising frequency modulating a carrier of the CIS processor.
12. A cochlear implant comprising:
a receiver configured to receive sound containing a voiced component;
an extraction module configured to extract pitch information from said sound for the voiced component; and
an encoding module configured to add said pitch information into a continuous-interleaved-stimulation (CIS) processor of the cochlear implant, wherein a stimulation rate and position is covaried to encode the pitch information.
13. The cochlear implant of claim 12 , wherein the extraction module uses one of time-domain processing and spectral-domain processing.
14. The cochlear implant of claim 12 , wherein the extraction module is further configured to extract a slowly-varying frequency modulation (FM) signal from said sound.
15. The cochlear implant of claim 14 , wherein extraction module comprises a phase vocoder to extract the slow-varying FM signal, and wherein the slow-varying FM signal is extracted around a center frequency of an analysis filter of the phase vocoder.
16. The cochlear implant of claim 14 , wherein the encoding module is further configured to add the slow-varying FM signal into the CIS processor.
17. The cochlear implant of claim 14 , further comprising a code-excited linear predictive (CELP) vocoder configured to use the slow-varying FM signal.
18. The cochlear implant of claim 17 , wherein the CELP vocoder comprises a codebook containing distinguishable temporal patterns, and wherein said code book is available to the CIS processor.
19. The cochlear implant of claim 18 , wherein the codebook in is stored in an implantable part of the cochlear implant.
20. The cochlear implant of claim 14 , wherein the encoding module is configured to map the pitch information to a set of basal electrodes of the cochlear implant.
21. The cochlear implant of claim 20 , wherein the encoding module is further configured to map temporal envelopes to a set of apical electrodes of the cochlear implant.