US 5,396,560 A · Hearing aid incorporating a novelty filter

Abstract

This invention discloses a hearing aid including one or more amplification channels in which each amplification channel includes a bandpass filter establishing the frequency range of that particular channel. Each amplification channel further includes a variable gain amplifier, a short-term energy averaging circuit, a long-term energy averaging circuit and a difference amplifier. An acoustical signal sensed by a microphone associated with the hearing aid is applied to the bandpass filter which then applies a signal within the particular frequency range of that filter to the variable gain amplifier and the short-term energy averaging circuit. An output from the variable gain amplifier is applied to the long-term energy averaging circuit and an earphone for enabling a hearing aid user to perceive the sounds sensed by the microphone. Steady state signals perceived by the microphone are integrated by the long-term energy averaging circuit which causes the difference amplifier to reduce the gain of the variable gain amplifier, thus decreasing the steady state sound. A novel sound sensed by the microphone is integrated by the short-term energy averaging circuit which causes the difference amplifier to increase the gain of the variable gain amplifier. In this manner, the gain of the amplifier is increased for desirable sounds and decreased for background noise.

Claims19

Dependent claims

A hearing aid comprising:

a microphone operable to sense acoustical events and convert them to proportionate electrical signals;
a variable gain amplifier operable to amplify the electrical signals from the microphone and provide an amplified output of that signal depending on the gain of the amplifier;
a difference amplifier operable to adjust the gain of the variable gain amplifier;
a long-term energy averaging circuit operable to sense substantially steady state acoustical events received by the microphone and force the difference amplifier to reduce the gain of the variable gain amplifier in view of the steady state signals;
a short-term energy averaging circuit operable to sense novel acoustical signals received by the microphone and force the difference amplifier to increase the gain of the variable gain amplifier in view of the novel signals;
and
an earphone operable to receive an output signal from the variable gain amplifier and convert it to an audible sound.

4 more elements

An amplifying circuit comprising:

a variable gain amplifier receiving an input signal and providing an amplified output of the input signal depending on the gain of the amplifier;
a difference amplifier having an output which adjusts the gain of the variable gain amplifier;
a long-term energy averaging circuit applying an input signal to a negative input of the difference amplifier for decreasing the gain of the variable gain amplifier, said long-term energy averaging circuit integrating substantially steady state signals of the input signal;
and
a short-term energy averaging circuit applying an input signal to a positive input of the difference amplifier for increasing the gain of the variable gain amplifier, said short-term energy averaging circuit integrating novel signals of the input signal.

2 more elements

A method of amplifying an acoustical event, said method comprising the steps of:

converting the acoustical event to a proportionate electrical signal:
applying the electrical signal as an input to a variable gain amplifier in order to amplify the signal depending on the gain of the amplifier;
applying an output from a difference amplifier to the variable gain amplifier in order to adjust the gain of the variable gain amplifier;
applying an output from a long-term energy averaging circuit to a negative input of the difference amplifier, wherein the long-term energy averaging circuit senses steady state portions of the signal in order to force the difference amplifier to reduce the gain of the variable gain amplifier;
applying an output from a short-term energy averaging circuit to a positive input of the difference amplifier, wherein the short-term energy averaging circuit integrates novel portions of the signal in order to force the difference amplifier to increase the gain of the variable gain amplifier;
and
converting an output of the variable gain amplifier to a proportionate acoustical signal.

4 more elements

Dependencies are inferred from the claim text.

Hearing aid incorporating a novelty filter

Life of this patent

Hearing aid incorporating a novelty filter

Life of this patent

Abstract

Claims19