Modeling external feedback path of an ITE digital hearing instrument for acoustic feedback cancellation

We describe a platform to facilitate research for the development of acoustic feedback cancellation algorithms to allow an increased gain from the hearing instrument (hearing aid) before the onset of unstable acoustic feedback. We describe an in-the-ear experimental system and compare its external feedback path (EFP) characteristics obtained by the sweep stimulus method and the white noise method. We show that the latter is preferred and verified the preciseness of the characteristics obtained. Finally, from the frequency domain characteristics of the EFP, we obtain its equivalent impulse response modeled by an adaptive LMS finite-impulse-response filter.