US 4,396,806 A · Hearing aid amplifier

Abstract

A general purpose hearing aid amplifier is programmably adaptable to the prescription requirements of the hearing impaired. The hearing aid amplifier comprises a bank of bandpass-restricted channels, each channel having a voltage-controlled input amplifier, a voltage-controlled compressor, and a voltage-controlled output amplifier for shaping the gain, attack and delay characteristics of the selected channel. The bank is fed through a fixed high-pass filter from a microphone input, and a mixed output drives a power amplifier for an output transducer such as a hearing aid speaker. The amplifier is programmably adaptable through the use of a monolithic programmable switch array using, for example, semiconductor fuseable link technology to preset digital-to-analog converters voltage controllable levels of the amplifiers and compressors of each channel according to a digital control input. The monolithic switch array is coupled to the programmable amplifiers through digital to analog converters which establish the programming voltages for the amplifiers and compressors. The monolithic switch array digital to analog converters may be constructed on the same monolithic semiconductor chip.

Claims6

Dependent claims

An apparatus for use as a hearing aid amplifier comprising:

a bank of bandpass-restricted channels, each channel having digitally-programmable amplifier means and digitally-programmable compressor means for shaping audio characteristics within each channel, each one of said channels being specific to a unique spectral region, the outputs of said channels being applied to a common output terminal;
a compact monolithic digital memory means comprising a programmable read only memory (PROM) operative to store binary states in bit storage cells without electrical power input, said binary states being permanently presettable external of said apparatus:
digital signal lines coupled to each one of said bit cells for use in conveying amplitude values of specified resolution represented by binary states of groups of said bit storage cells to said amplifier means and to said compressor means in each channel to preset parameters of said amplifier means and said compressor means;
and
digital signal applying means coupled to each one of said bit storage cells for directing digital signals originating external of said apparatus to said memory means for use in permanently presetting binary states of said bit storage cells.

2 more elements

Dependencies are inferred from the claim text.

Hearing aid amplifier

Life of this patent

Hearing aid amplifier

Life of this patent

Abstract

Claims6