Expansion as a Tool for Adaptation to Amplification

Abstract

Wide dynamic range compression (WDRC) has been successful at managing recruitment and reducing the discomfort of loud stimuli while making soft speech audible. However, WDRC can contribute to the complaint that hearing aids are noisy and that soft environmental sounds are abnormally loud. This situation can result in annoyance, stress, listener fatigue, and the possibility of a compromised signal-to-noise ratio for soft speech. Audio expansion is a tool that can be used to minimize these complaints. Although audio expansion has been in wide use as a noise reduction tool in telecommunications and professional audio for several decades, its use in hearing aids is comparatively recent. To understand better how expansion can be used to promote listener comfort and adaptation to hearing aid use, this article will present a basic review of expansion parameters. Subsequent sections will examine how expansion has been applied in hearing aids and how it behaves from a clinical standpoint. Finally, the use of expansion in multichannel WDRC hearing aid fittings will be discussed with a view toward improving listening comfort and helping new hearing aid users adapt to amplification.