US 4,049,930 A · Hearing aid malfunction detection system

Abstract

Disclosed is a malfunction detection system for detecting malfunctions in electrical signal processing circuits. In a particular embodiment shown, malfunctions of a hearing aid in the form of frequency distortion and/or inadequate amplification by the hearing aid amplifier, as well as weakening of the hearing aid power supply are detectable. A test signal is generated and a timed switching circuit periodically applies the test signal to the input of the hearing aid amplifier in place of the input signal from the microphone. The resulting amplifier output is compared with the input test signal used as a reference signal. The hearing aid battery voltage is also periodically compared to a reference voltage. Deviations from the references beyond preset limits cause a warning system to operate. In the method of the invention, the input to a circuit to be tested is periodically interrupted and, for a fixed test time interval, a test signal is applied to the circuit to be tested. The output of the circuit to be tested is compared with a reference signal, and deviation in amplitude and/or frequency between the two signals beyond preset limits triggers a warning. During the test time interval, the voltage level of the power supply for the circuit to be tested is also compared to a reference voltage, and the warning system is triggered if the power supply voltage falls below the reference voltage.

Claims28

Dependent claims

A system for detecting malfunctions in hearing aids by periodically applying a test signal at a first point of said hearing aid and comparing the resulting processed signal at a second point of said hearing aid with a reference signal comprising:

a. signal generation means for providing said test signal and said reference signal;
b. timed switching means for periodically applying said test signal at said first point of said hearing aid for a test time interval;
c. first difference detection means for comparing said processed signal with said reference signal to produce a first difference signal whose amplitude is a measure of difference between said processed signal and said reference signal;
and
d. warning system means for indicating whenever said amplitude of said first difference signal exceeds a first value.

2 more elements

A system for detecting malfunctions in electrical signal processing circuits comprising:

a. test signal generation means for generating a test signal characterized by a test frequency;
b. switch means for periodically interrupting signal processing by said electrical circuit for fixed test time intervals, and, during said test time intervals, transmitting said test signal to a first point in said electrical circuit for processing by said electrical circuit beyond said first point to a second point in said electrical circuit;
c. difference detection means, to which said test signal is transmitted from said test signal generation means as a reference signal, and to which said test signal, processed by said electrical circuit, is transmitted from said second point, and which compares the amplitude and frequency of said reference signal with that of said processed test signal to produce a difference signal responsive to said comparison;
d. gate means, to which said difference signal is transmitted, for outputting a trigger signal whenever said difference signal reaches a first amplitude value;
and
e. warning signal generation means, to which said trigger signal is transmitted, for producing a warning signal whenever said gate means outputs said trigger signal.

3 more elements

Dependencies are inferred from the claim text.

Hearing aid malfunction detection system

Life of this patent

Hearing aid malfunction detection system

Life of this patent

Abstract

Claims28