Effect of Hearing-Aid-Processed Speech on Brainstem Responses

Abstract

An ideal hearing aid is expected to have an output that is an exact replica of the input signal in terms of its spectral and temporal parameters. However, all of the commercially available hearing aids produce distortions in terms of spectral and temporal parameters of the signal. Such distortions of stimulus may affect the neuro-physiological processing and in turn the perception. In order to experimentally investigate this, the present study was taken up. Twenty nine adults with normal hearing and 22 adults with sensori-neural hearing loss participated in this study. A synthesized stimulus /da/ was processed through analog and digital hearing aids. Brainstem responses were recorded for the hearing aid processed /da/ as well as for unprocessed /da/ in normal and hearing impaired adults. Findings of this study suggest that hearing-aid-induced distortions affect amplitude and latency of the brainstem responses. Due to reduced temporal and spectral resolution in individuals with hearing impairment, auditory brainstem responses elicited from them were poorer compared to normal hearing individuals.