Patent ID: 8630437

Claim:
A hearing aid device comprising: a microphone configured to convert an acoustic input signal into an output signal; an equalization filter coupled to the microphone, the equalization filter configured to filter the output signal of the microphone to produce a filtered signal; an amplifier coupled to the equalization filter and configured to amplify the filtered signal to produce an amplified signal; a speaker coupled to the amplifier and configured to convert the amplified signal into an acoustic output signal; and an adaptive notch filter coupled to the equalization filter and configured to identify an offending frequency and provide a filter characteristic for the equalization filter to suppress the offending frequency by processing any of the output signal of the microphone and the filtered signal, wherein the adaptive notch filter comprises an estimator configured to estimate a variability of an adaptive notch filter parameter, and wherein an offending frequency is identified when the variability is less than a variability threshold value.