Technical Program

Paper Detail

Paper:	AE-P2.8
Session:	Hearing Aids, Auditory Models and Physical Models
Time:	Wednesday, May 17, 16:30 - 18:30
Presentation:	Poster
Topic:	Audio and Electroacoustics: Auditory Modeling and Hearing Aids
Title:	Howling Suppression in Hearing Aids using Least-Squares Estimation and Perceptually Motivated Gain Control
Authors:	Ashutosh Pandey, V. John Mathews, University of Utah, United States
Abstract:	Howling is a significant problem even in digital hearing aids equipped with adaptive feedback cancellation. Among the many causes of howling is the inability of the adaptive filter to track rapid changes in the feedback path. Many systems use howling detectors to detect the start of howling and reduce the hearing aid gain for several seconds to avoid prolonged howling. Unfortunately the inadequate speech pressure levels (SPL) during times when the gain is reduced causes loss of information and reduced intelligibility of speech signals arriving at the patient's ears. This paper presents a new method that switches to a least-squares adaptation scheme with linear complexity at the onset of howling. The method adapts to the altered feedback path quickly and allows the patient to not lose perceivable information. The complexity of the least-squares estimate is reduced by reformulating the least-squares estimate into a Toeplitz system and solving it with a direct Toeplitz solver. In addition, the gain function is changed immediately after howling detection in such a way that the system operates in a stable manner and the distortions caused are not perceived because of temporal masking. Simulation results comparing with a conventional method is presented in the paper to demonstrate the superior howling suppression capabilities of the method.