Effect of Sensorineural Hearing loss and Digital Hearing Aids on Speech Evoked Auditory Late Latency Response

Abstract

The aim of present study was to compare the auditory late latency response (ALLR) obtained for naturally produced speech tokens, /ba/, /da/, and /gal in unaided and aided conditions for different degrees of sensorineural hearing loss and also to evaluate the usefulness of ALLR in selection of amplification device using serally produced speech tokens. Two groups of participants including 12 individuals (12 ears) with normal hearing in the age range of 20 to 50 years and 25 individuals (35 ears) with hearing impairment in the age range of 20 to 50 years participated in the study. Individuals with sensorineural hearing loss were further sub- divided into 3 groups based on degree of hearing loss (moderate, moderately -severe and severe). Functional ain measurement as well as speech evoked ALLR were done both in unaided an aided conditions with two pre-selected digital hearing aids with first fit. For all the four groups, there was difference in response elicited by three speech stimuli. Individuals with normal hearing had longer latencies than those in the aided condition. Syllable /gal elicited longer latency and /ba/ elicited the least, response from Ida/ lied in between. For clinical group, latency for /gal was shortest and Ida/ was longest out of the three stimuli . Most of the subjects with hearing loss showed increased amplitude, decreased latency and improved waveform morphology in the aided condition but the response change was variable across individuals. From the results it can be concluded that, aided ALLR can help in selection of hearing aids as it mimics the hearing aid pro cessing. It also helps to assess the speech perception ability of the cortical structures objectively.