Patent ID: 6879692

Claim:
A hearing aid comprising an input transducer for transforming an acoustic input signal into a first electrical signal, a filter bank with bandpass filters for deriving from the first electrical signal a set of bandpass filtered derivatives of the first electrical signal, a signal processor for individual processing of each of the bandpass filtered derivatives of the first electrical signal and adding together the processed electrical signals to provide a second electrical signal based on the first electrical signal, an output transducer for converting the second signal into sound, a probe adapted for being selectively connected to the outputs of each one of said bandpass filters for determining a respective signal parameter, a test signal generator adapted for injecting a test signal at a selected point in the signal path of the hearing aid extending through said input transducer, said signal processor and said output transducer, a test controller adapted to control a state of the hearing aid, to receive an input from said probe and to determine any defect in the hearing aid, and activation means for operator activation in order to cause said test controller to initiate a test procedure.