Measurement of speech quality as a tool to optimize the fitting of a hearing aid.

The purpose of the present research was to develop a theoretical basis for the adjustment of hearing aid frequency response based on speech quality measurements. Speech quality measurements were made using continuous discourse and a category rating procedure for the following dimensions: intelligibility, pleasantness, loudness, effort, noisiness, and total impression. Speech quality ratings were obtained from a group of listeners with hearing loss who wore hearing aids. The stimulus conditions simulated hearing aid frequency response alterations within a frequency response range where intelligibility was held constant at or near 100%. The subject ratings revealed that (a) different listeners interpreted the individual dimensions in different ways; (b) within listeners, most of the dimensions were unique; that is, they were rated differently; and (c) across listeners, pleasantness was the dimension most highly correlated with total impression.