Speech perception abilities in individuals with auditory neuropathy spectrum disorder with preserved temporal synchrony

Abstract

Background:The auditory brainstem response (ABR) is usually abnormal in individuals with auditory neuropathy spectrum disorder (ANSD). However, in some such individuals the ABR is preserved at low repetition rates. This study attempts to understand the speech perception abilities of ANSD individuals who have preserved temporal synchronicity.Material and Methods:There were 149 individuals with ANSD in the study. They were classified into two groups based on preserved or absent ABR. Speech identification scores (SISs) in these individuals in quiet and in the presence of noise were compared.Results:At low repetition rates some 12.5% of subjects had preserved ABR with low amplitude wave V. Of these, 81% had an SIS of more than 50% in quiet. However, in patients with absent ABR, only 27% of individuals had an SIS of more than 50%. For subjects who had preserved ABR the mean SIS was 73.1% in quiet and 36.5% in noise compared to 35.9% in quiet and 20.2% in noise for individuals who had absent ABR.Conclusions:One in eight of the patients with ANSD had preserved ABR. Speech understanding was also better in quiet and in the presence of noise in individuals with preserved ABR. We conclude that speech reception abilities depend upon neural synchronicity at the level of the auditory nerve.