Detection of Speech Stimuli at Cortex in Children Using Hearing Aids: An Evidence from Speech Evoked Cortical Potential

Abstract

The present study aimed was to check speech evoked cortical potentials latencies and amplitude measures at different intensity levels (75 dB SPL, 65 dB SPL& 55 dB SPL) using different speech stimuli (/m/, /t/ & /g/) in children using hearing aids and compared with age-matched typically developing children. There were 44 children (17 children with normal hearing and 27 children using hearing aids) in the age range of 2 to 5 years participated in the present study. The recorded cortical auditory evoked potentials were marked for the two major peaks (P1 & N2) for each stimulus and at each intensity level in both the groups. The results showed that in general the mean latency measures at each speech stimulus and at each intensity level were prolonged (poorer) in children using hearing aids in comparison to typically developing children. Similarly, mean amplitude measures at each intensity for each speech stimulus was reduced (poorer) in children using hearing aids compared to typically developing children. However, there were no statistically significant effects of speech stimuli (/m/, /t/, & /g/) noticed at each intensity level for both latency as well as amplitude measures (P1 & N2) in children using hearing aids and typically developing children. In addition, it was observed in the present study that the CAEP responses were reduced in hearing aid users as the intensity level was reduced from 75 to 55 dB SPL. To conclude, hearing aid users showed prolonged latency and reduced amplitude for wave P1 and N2 in comparison to agematched typically developing children. The above finding probably indicates that hearing aid users are able to detect the different speech stimulus at each intensity level which indicates stimulation of different frequency regions at cortex.