Cochlear implants and apparatus/methods for improving audio signals by use of frequency-amplitude-modulation-encoding (FAME) strategies

• US 20030044034A1
• Filed: 08/27/2002
• Published: 03/06/2003
• Est. Priority Date: 08/27/2001
• Status: Active Grant

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Zeng, Fan-Gang, Nie, Kai-Bao
• Granted Patent: US 7,225,027 B2
• Time in Patent Office: Days
• US Class Current: 381/317
• CPC Class Codes: A61N 1/36036 of the outer, middle or inner ear
• CPC Class Codes: A61N 1/36038 Cochlear stimulation
• CPC Class Codes: H04H 20/48 for FM stereophonic broadcast systems
• CPC Class Codes: H04H 20/49 for AM stereophonic broadcast systems
• CPC Class Codes: H04R 25/356 Amplitude, e.g. amplitude shift or compression
• CPC Class Codes: H04R 25/505 using digital signal processing

Abstract

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.

Claims

1. A method for improving sound quality of an analog acoustic signal that is digitally processed, the method comprising the steps of:

a) extracting amplitude modulations and frequency modulations of at least one narrow band of the analog acoustic signal; and

b) filtering and compressing the modulations extracted in step (a) to produce amplitude modulated and frequency modulated acoustic signals that are digitally processed to provide an acoustic signal similar to the analog acoustic signal.

2. The method of claim 1, wherein the method is used to improve sound quality perceived by a person having a cochlear implant, and the method further comprises a step of:

c) stimulating electrodes of the cochlear implant with band-specific frequency and amplitude modulations.

3. The method of claim 1, wherein the method is used to recover broad-band qualities of the analog acoustic signal from a narrow-band transmission of the amplitude and frequency modulations, and the method further comprises a step of:

c) resynthesizing the amplitude and frequency modulations to generate an acoustic signal perceptually similar to the analog acoustic signal.

4. The method of claim 1, further comprising a step of:

dividing the analog acoustic signal into at least one narrow-band acoustic signal.

5. The method of claim 1, wherein the step of extracting the amplitude modulation comprises a step of rectifying and low-pass filtering the narrow band of the analog acoustic signal.

6. The method of claim 1, wherein the step of extracting the frequency modulation comprises a step of calculating an instantaneous phase angle of the narrow band of the analog acoustic signal at a region where the amplitude of the acoustic signal is approximately zero.

7. The method of claim 1, wherein step (b) comprises a step of modulating the amplitude of an extracted temporal envelope from step (a) to a frequency modulated carrier to create a band-specific frequency-amplitude modulated waveform.

8. The method of claim 7, wherein the step of modulating the amplitude of the extracted temporal envelope comprises a step of calculating a square root of the sum of a square of a first amplitude at a first time point and a square of a second amplitude at a second time point.

9. The method of claim 7, further comprising a step of summing the acoustic waveforms from a plurality of narrow bands to produce an acoustic simulation.

10. The method of claim 6, wherein the method comprises measuring a first amplitude at a first time and measuring a second amplitude at a second time, and calculating the arc tangent of the quotient of the second amplitude and the first amplitude.

11. 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 to stimulate the electrodes, the acoustic signal encoder encoding acoustic signals by (a) extracting amplitude and frequency modulations of at least one narrow band of an analog acoustic signal; and

(b) filtering and compressing the modulations extracted in step (a) to produce amplitude and frequency modulated acoustic signals that are used to stimulate the at least one electrode of the cochlear implant.

12. The cochlear implant of claim 11, 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.

13. The cochlear implant of claim 11, comprising an amplitude modulator.

14. The cochlear implant of claim 11, comprising a plurality of electrodes.

15. The cochlear implant of claim 14, 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.

16. An audio signal compression system, comprising:

at least one transmitter structured to receive an audio signal;

a plurality of data communication channels;

at least one receiver in communication with the at least one transmitter over the plurality of data communication channels; and

an audio signal encoder that encodes audio signals by (a) extracting amplitude and frequency modulations of at least one narrow band of an analog acoustic signal; and

(b) filtering and compressing the modulations extracted in step (a) to produce amplitude and frequency modulated acoustic signals that are transmitted over the data communication channels to the at least one receiver.

17. The system of claim 16, wherein the data communication channels are wireless channels.

18. The system of claim 16, wherein the receiver is configured to restore and synthesize the amplitude and frequency modulated signals to generate an audio signal acoustically similar to the audio signal received by the transmitter.

19. The system of claim 16, wherein the transmitter compresses the audio signals so that the signal information is transmitted over the data communication channels at a rate not greater than approximately 5 kbits/second.

20. The system of claim 16, wherein the transmitter transmits the signal information without center frequency information of the audio signal.