Frequency selection circuit for hearing aids
AssigneeArgosy Electronics, Inc.
InventorsDavid A. Preves, William A. Johnson
Life of this patent
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Abstract
A signal processing circuit for hearing aids includes a broadband peak detector for generating a control voltage based upon the sound pressure level of an incoming acoustical signal over its entire frequency spectrum. The control signal is used to determine the cut-off frequency of a voltage controlled adaptive high-pass filter. An amplified electrical signal, corresponding to the acoustical signal, also is provided to the high-pass filter. In setting the cut-off frequency, the control voltage causes the high-pass filter to selectively suppress the low frequency portion of the signal, generating a modified signal in which the noise component is reduced.
Claims17
A signal processing circuit for a hearing aid, including:
- a sound pressure level sensing means for sensing an audio signal and genernating an electrical signal corresponding to said sensed audio signal;
- a broadband signal amplifying means for amplifying said electrical signal to produce an amplified electrical signal;
- a broadband detecting means, having as an input substantially the entire frequency spectrum of said amplified electrical signal, said detecting means generating an output comprising a control signal having a control signal level proportional to said amplified electrical signal substantially over said entire frequency spectrum;
- an adaptive high-pass filtering means, having as a first input said amplified electrical signal, and as a second input said control signal, for selectively suppressing a low frequency portion of said amplifier electrical signal to generate a selectively modified signal, the frequency bandwidth of said suppressed low frequency portion, relative to the width of the entire frequency spectrum of said amplified electrical signal, increasing with said control signal level;
- and
- a receiver means for generating an audio signal corresponding to said selectively modified signal.
A process for selectively enhancing a portion of the frequency spectrum of an audio signal, including the steps of:
- sensing an audio signal, generating an electrical signal corresponding to the audio signal, and amplifying said electrical signal to produce an amplified electrical signal;
- generating a direct current signal, having a control voltage proportional to the level of said amplified electrical signal over substantially the entire frequency spectrum of said amplified electrical signal;
- selectively filtering said amplified electrical signal to suppress a low frequency portion of said amplified electrical signal to generate a modified electrical signal, while simultaneously applying said control voltage to determine the ratio of the bandwidth of to said low frequency portion of the bandwidth of said entire frequency spectrum of said signal, said ratio increasing and decreasing as said control voltage increases and decreases, respectively;
- and
- generating a selectively enhanced audio signal corresponding to said modified electrical signal.
A signal processing circuit for a hearing aid, including:
- a sound pressure level sensing means for sensing an audio signal and generating an electrical signal corresponding to said sensed audio signal;
- a broadband signal amplifying means for amplifying said electrical signal to produce an amplified electrical signal;
- a broadband detecting means, having as an input substantially the entire frequency spectrum of said amplified electrical signal, for generating a control signal having a control signal level proportional to said amplified electrical signal;
- an adaptive high-pass filtering means, having as a first input said amplified electrical signal, and as a second input said control signal, for selectively suppressing a selected portion of said amplified electrical signal to generate a selectively modified signal, wherein said selected portion includes at least low range frequencies of said amplified electrical signal and wherein the frequency bandwidth of said suppressed selected portion, relative to the bandwidth of the entire frequency spectrum of said amplified electrical signal, increases with the level of said control signal;
- and
- receiver means for generating an audio signal corresponding to said selectively modified signal.
Dependencies are inferred from the claim text.