Heating aid with acoustic feedback suppression

A method of reducing acoustic feedback of a hearing aid comprising an input transducer for transforming an input signal into an electrical input signal, a signal processor for generating an electrical output signal and an output transducer for transforming the electrical output signal into an acoustic output signal, comprising the steps of:

• generating an adaptive feedback cancellation signal,
• subtracting the feedback cancellation signal from the electrical input signal generating a feedback-cancelled input signal,
• generating a first norm signal indicative of a norm Nx of the electrical input signal and a second norm signal indicative of a norm Nfbc of the feedback-cancelled input signal,
• comparing the first norm signal with the second norm signal and thereby generating a difference value Nfbc−Nx, and
• disabling application of the feedback cancellation signal into the signal path of the hearing aid if the difference value Nfbc−Nx is above a certain threshold value cth.

A computer program comprising program code for performing a method of reducing acoustic feedback of a hearing aid comprising an input transducer for transforming an input signal into an electrical input signal, a signal processor for generating an electrical output signal and an output transducer for transforming the electrical output signal into an acoustic output signal, said computer program comprising code steps for:

• generating an adaptive feedback cancellation signal,
• subtracting the feedback cancellation signal from the electrical input signal generating a feedback-cancelled input signal,
• generating a first norm signal indicative of a norm Nx of the electrical input signal and a second norm signal indicative of a norm Nfbc of the feedback-cancelled input signal,
• comparing the first norm signal with the second norm signal and thereby generating a difference value Nfbc−Nx, and
• disabling application of the feedback cancellation signal into the signal path of the hearing aid if the difference value Nfbc−Nx is above a certain threshold value cth.

An electronic circuit for a hearing aid comprising:

• a signal processor for processing an electrical input signal, derived from an acoustic input signal, and generating an electrical output signal,
• an adaptive filter for generating a feedback cancellation signal,
• a means for subtracting the feedback cancellation signal from the electrical input signal to generate a feedback-cancelled input signal,
• a norm estimator for generating a first norm signal indicative of a norm Nx of the electrical input signal and for generating a second norm signal indicative of a norm Nfbc of the feedback-cancelled electrical input signal,
• a comparator for comparing the first norm signal with the second norm signal and generating a difference value Nfbc−Nx between the norm of the feedback-cancelled input signal and the norm of the electrical input signal, and
• a decision unit disabling the application of the feedback cancellation signal into the signal path of the hearing aid if the difference value is above a certain threshold value.