Influence of hearing aid compression speed and channels on measures of psychophysical tuning curves

Abstract

While much work has been completed on spectral resolution in listeners with SNHL, little attention has been paid to the impact of hearing-aid signal processing on access to spectral information. In this study, we hypothesized that increasing the hearing aid compression speed and number of compression channels would improve access to spectral information by providing better audibility across frequency. However, limited outer hair cell function or inhibition could curtail the benefit of improved audibility on spectral resolution. In this experiment, psychophysical tuning curves were measured for 25 participants with hearing loss. Both an excitation and phenomenological model of the auditory system were used to examine potential mechanisms that contributed to the observed results. The provision of amplification improved the measured sharpness of tuning for the low-frequency side. While decreasing the compression speed did not have a systematic effect on the measured psychophysical tuning curves, the low frequency side improved as the number of compression channels was increased. Threshold estimates from the excitation and phenomenological models were able to account for some of these observed trends in the psychophysical tuning curves, but the threshold estimates from the phenomenological model were more consistent with the measured thresholds.