Speech-Evoked Auditory Late Latency Response (ALLR) in hearing aid selection

Abstract

Cortical auditory evoked potentials (CAEPs) offer the possibility of evaluating the effectiveness of hearing instruments in infants and older children who have limited behavioural repertoire due to developmental delay or other disabilities. The present study was an attempt to investigate the usefulness of auditory late latency responses (ALLR) evoked using speech stimuli in hearing aid selection. The study consisted of two groups of participants. Group I included children with normal hearing and Group II included children with hearing impairment both in the age range of 5-7 years. CAEPs/ALLR were recorded for Group I participants for three naturally produced speech sounds, /i/, /m/, /∫/, presented through a loud speaker at 65 dB SPL. The CAEPs/ALLR was recorded for the same stimuli without a hearing aid and with two pre selected hearing aids for Group II. For Group II participants functional gain measurements were also carried out with the two pre selected hearing aids. The CAEPs (P1-N1-P2-N2) were analyzed for peak latencies and amplitude of N1-P2 complex. Analyses of the data revealed that all the three stimuli elicited waveforms that were distinct from each other. Significant effect of stimuli was demonstrated for children with normal hearing and children with hearing impairment wearing a hearing aid. Significant effect of age was not observed though a trend of decrease in latency was noted for children with normal hearing. Comparison between aided and unaided conditions revealed that in unaided conditions the responses were absent but the responses were present in the aided condition. There was no statistically significant difference between the latencies and amplitude of CAEP/ALLR peaks for the two populations when the children with hearing impairment were wearing the most appropriate hearing aid. These findings highlight that P1-N1-P2-N2 responses are efficient in reflecting the benefit of hearing aid at least at a gross level.