Apparatus for eliminating acoustic oscillation in a hearing aid by using phase equalization

摘要

In a hearing aid, undesirable oscillations that are caused by acoustic feedback occur when the gain of the hearing aid amplifier is increased. These oscillations in the hearing aid system response are substantially suppressed by providing phase equalization that equalizes the phase of the microphone, amplifier, receiver and feedback path involved in the hearing aid. The phase equalization can be provided directly in the signal path at the output of the amplifier or by a separate inner loop feedback around the amplifier. The phase equalization can be provided by one or more first or second order filters that operate as an all-pass filter to provide a time delay but do not affect the magnitude of the signal in the audio frequency range.