Design Guidelines for Feedforward Cancellation of the Occlusion-Effect in Hearing Aids

The occlusion-effect is described as an unsatisfactory quality of the hearing-aid user's own voice that sounds hollow or boomy. Some fixed and adaptive feedback controllers have been suggested in order to reduce the occlusion-effect. More recently, a feedforward adaptive active-noise-control based strategy for unvented hearing aids was proposed. This paper presents a theoretical analysis of the convergence conditions for this canceller. This allows explicit analytical determination of its stability limits, providing an adequate setup of the algorithm parameters to achieve a priori performance requirements, such as convergence speed and sound quality. Design examples are presented, which validate the theoretical analysis and illustrate its practical application.