Enhanced signal processing for cochlear implants
First Claim
1. A method for processing an audio input to generate a signal for controlling a cochlear implant for a hearing impaired patient, the method comprising the steps of:
- (a) providing an auditory input signal;
(b) performing a coherent demodulation of the auditory input signal to generate a frequency shifted signal, using a targeted temporal pitch trajectory comprising a frequency range of about 50 Hz to about 300 Hz;
(c) processing the frequency shifted signal to generate a relatively low frequency, slowly varying signal that is compatible with the cochlear implant; and
(d) mapping the relatively low frequency, slowly varying signal to at least one of a plurality of cochlear implant stimulation electrodes.
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Abstract
The restoration of melody perception is a key remaining challenge in cochlear implants. A novel sound coding strategy is proposed that converts an input audio signal into time-varying electrically stimulating pulse trains. A sound is first split into several frequency sub-bands with a fixed filter bank or a dynamic filter bank tracking harmonics in sounds. Each sub-band signal is coherently downward shifted to a low-frequency base band. These resulting coherent envelope signals have Hermitian symmetric frequency spectrums and are thus real-valued. A peak detector or high-rate sampler of half-wave rectified coherent envelope signals in each sub-band further converts the coherent envelopes into rate-varying, interleaved pulse trains. Acoustic simulations of cochlear implants using this new technique with normal hearing listeners, showed significant improvement in melody recognition over the most common conventional stimulation approach used in cochlear implants.
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Citations
24 Claims
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1. A method for processing an audio input to generate a signal for controlling a cochlear implant for a hearing impaired patient, the method comprising the steps of:
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(a) providing an auditory input signal; (b) performing a coherent demodulation of the auditory input signal to generate a frequency shifted signal, using a targeted temporal pitch trajectory comprising a frequency range of about 50 Hz to about 300 Hz; (c) processing the frequency shifted signal to generate a relatively low frequency, slowly varying signal that is compatible with the cochlear implant; and (d) mapping the relatively low frequency, slowly varying signal to at least one of a plurality of cochlear implant stimulation electrodes. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method for controlling a cochlear implant for a hearing impaired patient, the method comprising the steps of:
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(a) providing an auditory input signal; (b) determining a pitch of the auditory input signal over time; (c) separating the auditory input signal into a plurality of harmonics over time as a function of the pitch over time; (d) for each of the plurality of harmonics, shifting the frequency of the harmonic downward, generating a plurality of frequency shifted harmonics; (e) for each frequency shifted harmonic, performing an amplitude modulation, generating a plurality of frequency shifted and amplitude modulated harmonics; and (f) mapping each frequency shifted and amplitude modulated harmonic to different ones of a plurality of cochlear implant stimulation electrodes. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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18. A cochlear implant for a hearing impaired patient, comprising:
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(a) at least one acoustic sensor for providing an auditory input signal; (b) a power supply; (c) a plurality of stimulation electrodes; and (d) a processor for controlling the plurality of stimulation electrodes based on the auditory input signal, the processor implementing the functions of; (i) performing a coherent demodulation of the auditory input signal to generate a frequency shifted signal, using a targeted temporal pitch trajectory comprising a frequency range of about 50 Hz to about 300 Hz; (ii) processing the frequency shifted signal to generate a relatively low frequency, slowly varying signal that is compatible with the cochlear implant; and (iii) mapping the relatively low frequency, slowly varying signal to at least one of the plurality of stimulation electrodes. - View Dependent Claims (19, 20, 21, 22, 23)
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24. A cochlear implant for a hearing impaired patient, comprising:
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(a) at least one acoustic sensor for providing an auditory input signal; (b) a power supply; (c) a plurality of stimulation electrodes; and (d) a processor for controlling the plurality of stimulation electrodes based on the auditory input signal, the processor implementing the functions of; (i) determining a pitch of the auditory input signal over time; (ii) separating the auditory input signal into a plurality of harmonics over time as a function of the pitch over time; (iii) for each of the plurality of harmonics, shifting the frequency of the harmonic downward, generating a plurality of frequency shifted harmonics; (iv) for each frequency shifted harmonic, performing an amplitude modulation, generating a plurality of frequency shifted and amplitude modulated harmonics; and (v) mapping each frequency shifted and amplitude modulated harmonic to at least one of a plurality of stimulation electrodes.
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Specification