Hearing aid amplifiers employing selective gain control circuits

Claim 2

A hearing aid device comprising: a. transducer means for providing electrical signals corresponding to received audio signals, b. gain controllable amplifier means coupled to said transducer means and operative to provide a relatively constant gain over a desired audio frequency, and c. means for varying the gain of said amplifier when the intensity of said audio signal exceeds a predetermined sound intensity level in the vicinity of forty decibels; whereby the gain of said controllable amplifiers remains constant for all intensity levels below said vicinity and is decreased for all intensity levels above said vicinity of forty decibels; said means for varying the gain including first and second detecting means, said first means responsive to the peak value of certain of said audio signals in excess of said level and said second means responsive to the average value of all audio signals in excess of said intensity level for varying the gain of said amplifier according to such both said first and second means.

Claim 3

A hearing aid device comprising: a. transducer means for providing electrical signals corresponding to received audio signals, b. first gain controllable means including an average detector coupled to said transducer means and operative to provide a relatively constant gain for a first range of audio signals of an intensity between 0 and 50 decibels, and c. second controllable means including a peak detector responsive to audio signals in excess of the upper range of intensity to decrease the gain of said amplifier for all input signals above said desired range.

Claim 4

A hearing aid device comprising: a. transducer means for providing electrical signals corresponding to received audio signals, b. first gain controllable means including an average detector coupled to said transducer means and operative to provide a relatively constant gain for a first range of audio signals of an intensity between 0 and 50 decibels, and c. second controllable means including a peak detector responsive to audio signals in excess of the upper range of intensity to decrease the gain of said amplifier for all input signals above said desired range.

Claim 5

A hearing aid device comprising a. transducer means for producing electrical signals corresponding to received audio signals, b. a gain controllable amplifier coupled to said transducer means and operative to provide a relatively constant gain for a first range of said audio signals of an intensity between 0 to 50 decibels, c. a selective filter responsive to a given frequency range of said audio signals indicative of desired audio information to provide at an output, audio signals encompassed within said given frequency range, d. first detecting means responsive to the peak value of said signals within said range to provide a control output signal when said peaks are in excess of the upper limit of said first range, e. second detecting means responsive to the average value of all audio signals to provide a second control signal when the intensity of all audio signals exceed the upper limit of said first range, f. combining means operative to provide an output signal during the presence of said first or second control signal, g. gain control means responsive to said output signal of said combining means to vary the gain of said amplifier during the presence of said first or second control signals.

Claim 6

A hearing aid device comprising a. transducer means for producing electrical signals corresponding to received audio signals, b. a gain controllable amplifier coupled to said transducer means and operative to provide a relatively constant gain for a first range of said audio signals of an intensity between 0 to 50 decibels, c. a selective filter responsive to a given frequency range of said audio signals indicative of desired audio information to provide at an output, audio signals encompassed within said given frequency range, d. first detecting means responsive to the peak value of said signals within said range to provide a control output signal when said peaks are in excess of the upper limit of said first range, e. second detecting means responsive to the average value of all audio signals to provide a second control signal when the intensity of all audio signals exceed the upper limit of said first range, f. combining means operative to provide an output signal during the presence of said first or second control signal, g. gain control means responsive to said output signal of said combining means to vary the gain of said amplifier during the presence of said first or second control signals.

Claim 7

The hearing aid device according to claim 3 wherein said selective filter operates within the range of 600 to 1100 Hertz.

Claim 8

The hearing aid device according to claim 3 wherein said first detecting means consist of a peak detector circuit.

Claim 9

The hearing aid device of claim 3 wherein said combining means consist of an OR gate.

Claim 10

The hearing aid device according to claim 3 wherein said gain control means comprise: a. a Schmitt trigger operative to provide a bias signal upon application to an input of said output signal, b. a differential amplifier responsive to said bias signal and having an output coupled to said gain controllable amplifier for varying the gain only during the presence of said bias signal.

Claim 11

The device according to claim 7 further comprising: a. means for disabling said differential amplifier to enable operation of said gain controllable amplifier at said relatively constant gain.

Claim 12

The hearing aid device according to claim 3 further including frequency compensating means coupled to said gain controllable amplifier.

Claim 13

The hearing aid device according to claim 7 wherein said differential amplifier includes a constant current source transistor having a base electrode responsive to said bias signal emanating from said Schmitt trigger to cause said differential amplifier to operate.