Method and apparatus for simulating aural response information
First Claim
1. A method for simulating neural response of an ear comprising:
- filtering an input signal representative of sound stimuli through a first filtering means, said first filtering means producing first response characteristics to said stimuli, said first response characteristics being divided into a plurality of channels as channelized frequency band limited signals;
thereafterhalf-wave detecting each one of said channelized frequency band limited signals representative of said first response characteristics over a relatively broad band to produce a plurality of frequency channelized detected signals;
compressing said frequency channelized detected signals in each said channel as a function of amplitude of frequency channelized detected signals in other channels to produce output electronic signals; and
providing said electronic output signals to an output utilization means.
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Abstract
Speech and like signals are analyzed based on a model of the function of the human hearing system. The model of the inner ear is expressed as signal processing operations which map acoustic signals into neural representations. Specifically, a high order transfer function is modeled as a cascade/parallel filterbank network of simple linear, time-invariant second-order filter sections. Signal transduction and compression are based on a half-wave rectification with a non-linearly coupled, variable time constant automatic gain control network. The result is a simple device which simulates the complex signal transfer function associated with the human ear. The invention lends itself to implementation in digital circuitry for real-time or near real-time processing of speech and other sounds.
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Citations
19 Claims
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1. A method for simulating neural response of an ear comprising:
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filtering an input signal representative of sound stimuli through a first filtering means, said first filtering means producing first response characteristics to said stimuli, said first response characteristics being divided into a plurality of channels as channelized frequency band limited signals;
thereafterhalf-wave detecting each one of said channelized frequency band limited signals representative of said first response characteristics over a relatively broad band to produce a plurality of frequency channelized detected signals; compressing said frequency channelized detected signals in each said channel as a function of amplitude of frequency channelized detected signals in other channels to produce output electronic signals; and providing said electronic output signals to an output utilization means. - View Dependent Claims (2, 3, 4)
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5. A method for simulating neural response of an ear comprising:
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separating an input signal into a plurality of channels of frequency band-limited signals, each band-limited signal having a different time delay relative to said input signal associated therewith, said separating comprising combining a plurality of notch filters arranged in cascade with a plurality of resonant bandpass filters arranged in parallel, each said bandpass filter being coupled to receive said input signal through a different number of notch filters; detecting each one of said band-limited signals to produce a plurality of corresponding channelized output signals; and providing said channelized output signals to an output utilization means. - View Dependent Claims (6, 7, 8, 9)
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10. An apparatus for processing an input signal having information distributed in time and frequency comprising:
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means responsive to said input signal for separating said input signal into a plurality of frequency band-limited signals, each band-limited signal having a different time-delay relative to said input signal associated therewith; means for half-wave rectifying each one of said band-limited signals to produce rectified band-limited signals; and means for compression each one of said rectified band-limited signals in proportion to amplitude of corresponding rectified band-limited signals and in proportion to other ones of said rectified band-limited signals to produce a plurality of compressed, rectified band-limited channelized output signals distributed in time. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. An apparatus for processing an input signal having information distributed in time and frequency comprising:
means responsive to said input signal for separating said input signal into a plurality of frequency band-limited signals, each band-limited signal having a different time delay relative to said input signal associated therewith, said separating means comprising a combination of a plurality of notch filters arranged in cascade with a plurality of resonant bandpass filters arranged in parallel, each said bandpass filter being coupled to receive said input signal through a different number of notch filters.
Specification