Cochlear implants and apparatus/methods for improving audio signals by use of frequency-amplitude-modulation-encoding (FAME) strategies
A method of improving sound quality of audio signals that are digitally processed includes steps of extracting amplitude and frequency modulations from one or more narrow bands of the audio signal, and filtering and compressing those modulations to produce amplitude and frequency modulated audio signals that are digitally processed to provide an acoustic signal similar to the original audio signal. The methods may be used in auditory prostheses and telecommunication systems.
1. A cochlear implant, comprising:
at least one electrode structured to be placed in a patient's cochlea; and
an acoustic signal encoder in communication with the at least one electrode and effective to stimulate the at least one electrode, the acoustic signal encoder comprising:
(a) an amplitude modulation extractor effective to extract amplitude modulations from at least one band of an acoustic signal,
(b) a frequency modulation extractor effective to extract frequency modulations from the at least one band of the acoustic signal, and
(c) a signal processor effective to compress the amplitude and frequency modulations to produce amplitude and frequency modulated electric signals that are used to stimulate the at least one electrode of the cochlear implant.
2. The cochlear implant of claim 1 , comprising a frequency modulator that modulates frequency of an acoustic signal so that an inter-pulse interval of the acoustic signal varies according to a frequency modulation pattern.
3. The cochlear implant of claim 1 , comprising an amplitude modulator.
4. The cochlear implant of claim 1 , comprising a plurality of electrodes.
5. The coohlear implant of claim 4 , comprising a pulse controller that controls positioning of frequency-amplitude-modulated pulses generated by the signal encoder to reduce simultaneous stimulation across the plurality of electrodes.
6. The cochlsar implant of claim 1 wherein the amplitude modulation extractor comprises a transformer.
7. The cochlear implant of claim 6 wherein the transformer is a Hilbert transformer.
8. The cochlear implant of claim 1 wherein the amplitude modulation extractor comprises a rectifier.
9. The cochlear implant of claim 1 wherein the amplitude modulation extractor comprises a low pass filter.
10. The cochlear implant of claim 1 wherein the amplitude modulation extractor comprises a rectifier/low pass filter.
11. The cochlear implant of claim 1 wherein the amplitude modulation extractor comprises a transformer and a rectifier/low pass filter.
12. The cochlear implant of claim 1 wherein the frequency modulation extractor comprises a band pass filter.
13. The cochlear implant of claim 1 wherein the signal processor is further effecUve to filter the amplitude and frequency modulations extracted from the at least one band.
14. The cochlear implant of claim 1 further comprising a pre-processor in communication with the signal encoder, the pre-processor being effective to divide a broad band acoustic signal into a plurality of narrow band signals that are passed to the signal encoder.
15. The cochlear implant of claim 14 which is effective to produce a band-specific frequency-amplitude modulated waveform that simulates the broad band acoustic signal provided to the pre-processor.
16. The cochlear implant of claim 1 wherein the at least one band comprises a plurality of bands and the signal encoder is effective to extract amplitude and frequency modulations from the bands on an individual basis.
17. The cochlear implant of 1 wherein the frequency modulation extractor is effective to calculate an instantaneous phase angle of the at least one band of the acoustic signal at a region of where the amplitude of the acoustic signal is approximately zero.
18. The cochlear implant of claim 1 wherein the amplitude modulation extractor is effective to extract a temporal envelope from the at least one band of the acoustic signal.
19. The cochlear implant of claim 18 wherein the signal processor is effective to modulate the amplitude of the extracted temporal envelope.