Feedback cancellation in hearing aids using constrained adaptation

In feedback cancellation in hearing aids, the output of an adaptive filter is subtracted from the microphone signal to cancel the acoustic and mechanical feedback signals picked up by the microphone. The feedback cancellation filter typically adapts the hearing-aid input signal, and signal cancellation and coloration artifacts can occur for a narrowband input. In this paper, two procedures for LMS adaptation with a constraint on the magnitude of the adaptive weight vector are derived. The constraints greatly reduce the probability that the adaptive filter will cancel a narrowband input. Simulation results are used to demonstrate the efficacy of the constrained adaptation.