Key issues in hearing aid selection and evaluation.

Abstract

This article examines three key issues in hearing aid selection and evaluation. First, two studies are analyzed to determine the extent to which differences in frequency response characteristics result in differences in judgments of the intelligibility or pleasantness of amplified speech. Small to moderate frequency response differences usually did result in different judgments although occasionally large differences did not. When two dissimilar responses are equally intelligible, it is likely that the best response is something in between them. Second, evidence indicates that it is not always satisfactory to allow frequency response to be determined by prescribing gain at each frequency separately. This suggests, therefore, that separate frequency response prescription rules are needed. Third, signal audibility is discussed in the context of using simplified Articulation Index schemes to predict aided performance. It is demonstrated how wrong conclusions may easily be drawn in the absence of accurate knowledge of the signal levels received when different hearing aid options are used. Data suggest that the Articulation Index may not be applicable to steeply sloping high-frequency hearing losses. This needs further investigation before the Articulation Index can be recommended for hearing aid evaluations.