Method and apparatus for envelope detection and enhancement of pitch cue of audio signals
AssigneesCochlear Limited, The University of Melbourne
InventorsBrett A. Swanson, Peter J. Blamey, Hugh J. McDermott, James F. Patrick
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Abstract
A method and apparatus for detecting an envelope of an audio signal, and a method and apparatus for enhancing the pitch cue of an audio signal perceived by a cochlear implant patient where the audio signal is processed and input to an implant device of the recipient. The methods and apparatuses use techniques such as filtering, rectifying, detecting peak values, sampling, resetting, comparing and multiplying various signals to detect the envelope or enhance the pitch cue of the audio signal.
Claims27
A method of detecting an envelope of an audio signal comprising the steps of:
- filtering the audio signal to produce a filtered audio signal;
- rectifying the filtered audio signal to produce a rectified signal;
- detecting peak values of the rectified signal to produce a detected signal;
- sampling the detected signal, at a frequency that is less than the frequency components in the filtered audio signal, to produce samples;
- and
- resetting the detected signal immediately after sampling.
A method of detecting an envelope of an audio signal comprising the steps of:
- filtering the audio signal to produce a filtered audio signal;
- rectifying the filtered audio signal to produce a rectified signal;
- detecting peak values of the rectified signal to produce a detected signal;
- sampling the detected signal at predetermined time intervals to produce samples;
- and
- resetting the detected signal immediately after sampling;
- wherein the detected peak values remain at a substantially constant value prior to the sampling step;
- and
- wherein the detected signal or detected signals is reset substantially to zero.
A method of enhancing the pitch cue of an audio signal perceived by a cochlear implant recipient, wherein the audio signal is processed and input to an implant device of the recipient, the method comprising the steps of:
- filtering the audio signal to produce a filtered audio signal;
- half-wave rectifying the filtered audio signal to produce a half-wave rectified signal;
- and
- sampling the half-wave rectified signal at a frequency greater than the frequency components in the filtered audio signal.
An apparatus for enhancing the pitch cue of an audio signal perceived by a cochlear implant recipient, the audio signal being processed and input to an implant device of the recipient, the apparatus comprising:
- means for filtering the audio signal to produce a filtered audio signal;
- means for half-wave rectifying the filtered audio signal to produce a half-wave rectified signal;
- and
- means for sampling the half-wave rectified signal at a frequency greater than the frequency components in the filtered audio signal.
An apparatus for enhancing the pitch cue of an audio signal perceived by a cochlear implant recipient, the audio signal being processed and input to an implant device of the recipient, the apparatus comprising:
- means for filtering the audio signal to produce a filtered audio signal;
- means for envelope detecting the filtered audio signal to produce an envelope detected signal;
- comparator means for producing a gating signal having one of two Boolean states;
- means for multiplying the gating signal with the envelope detected signal to produce a multiplied signal;
- and
- means for sampling the multiplied signal at predetermined time intervals.
A method of enhancing the pitch cue of an audio signal perceived by a cochlear implant recipient, wherein the audio signal is processed and input to an implant device of the recipient, the method comprising the steps of:
- filtering the audio signal to produce a filtered audio signal;
- and
- sampling the filtered audio signal to produce samples;
- wherein the samples are synchronized with one of positive phases and negative phases of the filtered audio signal.
A method of enhancing the pitch cue of an audio signal perceived by a cochlear implant recipient, wherein the audio signal is processed and input to an implant device of the recipient, the method comprising the steps of:
- filtering the audio signal to produce a filtered audio signal;
- and
- sampling the filtered audio signal to produce samples;
- wherein the samples are synchronized with the filtered audio signal;
- and
- wherein the sampling step uses a clock synchroniser that generates bursts of clock pulse separated by a fixed time interval with the leading pulse in each burst of pulses being synchronised to the phase of the filtered audio signal.
An apparatus for enhancing the pitch cue of an audio signal perceived by a cochlear implant recipient, the audio signal being processed and input to an implant device of the recipient, the apparatus comprising:
- means for filtering the audio signal to produce a filtered audio signal;
- and
- means for sampling the filtered audio signal at predetermined time intervals to produce samples;
- wherein the samples are synchronised with one of positive phases and negative phases of the filtered audio signal.
An apparatus for enhancing the pitch cue of an audio signal perceived by a cochlear implant recipient, the audio signal being processed and input to an implant device of the recipient, the apparatus comprising:
- means for filtering the audio signal to produce a filtered audio signal;
- and
- means for sampling the filtered audio signal at predetermined time intervals to produce samples;
- wherein the samples are synchronised with the filtered audio signal;
- and
- wherein the apparatus further comprises half-wave rectifying means connected between the filter means and the sampling means for half-wave rectifying the filtered audio signal to produce a half-wave rectified signal, and thereafter the sampling means sampling the half-wave rectified signal at predetermined intervals to produce samples that are synchronised with the filtered audio signal.
In a multiple channel cochlear implant system permitting sequential stimulation, a method of enhancing the pitch cue of an audio signal perceived by a cochlear implant recipient, wherein the audio signal is processed and input to an implant device of the recipient, the method comprising the steps of:
- filtering the audio signal to produce a filtered audio signal;
- sampling the filtered audio signal to produce samples;
- and
- synchronising the samples of the filtered audio signal using a selection means and a series of master clock pulses, such that on each master clock pulse no more than one channel is selected by the selection means.
Dependencies are inferred from the claim text.