Provided is an implanted hearing instrument having reduced sensitivity to vibration. In this regard, the instrument differentiates between the desirable and undesirable signals within an implanted microphone response. In one arrangement, an observer identifies a current operating state of the implanted hearing instrument and one or more cancellation filters are adjusted based on the current operating state. The cancellation filter(s) are used to reduce undesired signals form the implanted microphone response. In a first arrangement, the output of the implanted hearing instrument may be filtered and removed from the implanted microphone response to reduce or substantially eliminate feedback in the microphone signal provided to an implanted signal processor.