Abstract: A method for processing signals including an input, an output and a signal processor, comprising detecting a first periodic signal received at an input, adjusting frequency or phase of the first periodic signal in response to detecting the first periodic signal, comparing an amplitude of the first periodic signal before adjusting the frequency or phase to the amplitude after adjusting the frequency or phase to produce a first amplitude change and determining whether the first periodic signal is an acoustic feedback signal based on the first amplitude change. Apparatus including signal processing electronics to receive an input signal from a microphone and programmed to provide phase or frequency changes to signals in a processing channel and to detect periodic feedback signals based on the changes of signals in the processing channel, and a speaker. Variations include feedback reduction or cancellation systems and phase or frequency adjustment systems.

Abstract: Method and apparatus for entrainment containment in digital filters using output phase modulation. Phase change is gradually introduced into the acoustic feedback canceller loop to avoid entrainment of the feedback canceller filter. Various embodiments employing different output phase modulation approaches are set forth and time and frequency domain examples are provided. Additional method and apparatus can be found in the specification and as provided by the attached claims and their equivalents.

Abstract: A method of signal processing an input signal in a hearing aid to avoid entrainment, the hearing aid including a receiver and a microphone, the method comprising using an adaptive filter to measure an acoustic feedback path from the receiver to the microphone and adjusting an adaptation rate of the adaptive filter using an output from a filter having an autoregressive portion, the output derived at least in part from a ratio of a predictive estimate of the input signal to a difference of the predictive estimate and the input signal.

Abstract: Method and apparatus for entrainment containment in digital filters using output phase modulation. Phase change is gradually introduced into the acoustic feedback canceller loop to avoid entrainment of the feedback canceller filter. Various embodiments employing different output phase modulation approaches are set forth and time and frequency domain examples are provided. Additional method and apparatus can be found in the specification and as provided by the attached claims and their equivalents.