Extension and Evaluation of a Spectro-Temporal Modulation Method to Improve Acoustic Feedback Performance in Hearing Aids

Adaptive filters have been widely used for feedback cancellation in audio systems including hearing aids. However, the ability to cancel feedback in dynamic feedback situations is still a big challenge; the adaptive filters need to ensure a small enough steady-state error to facilitate sufficient amplification in hearing aids, hence their convergence rates are typically insufficient to handle fast feedback path changes. Recently, we proposed a novel method by using spectro-temporal modulation (STM) in the time-frequency regions where the adaptive filters have insufficient convergence rate. Applying STM prevents feedback to occur and replaces traditional loud/annoying feedback whistling sounds with soft/non-intrusive STM processed sounds. In this work, we introduce an extension to make the STM processed sound even less audible. Furthermore, we present novel evaluation results regarding feedback cancellation and sound quality from listening experiments, which confirm that without degrading sound quality in static feedback situations we significantly improve feedback cancellation performance upon fast feedback path changes.