Effect of Stimulus Rate on Subcortical Auditory Processing in Children

Abstract

Temporal processing that utilized the Auditory Brainstem Response audiometry (ABR) responses recorded at different rates have not studied the developmental changes during childhood. Aim of the present study: The primary aim of the present study was to investigate the interactions between auditory temporal processing and stimulus complexity by examining the effects of stimulus rate on speech and click-evoked ABR and Frequency following responses (FFR) in children. The secondary aim was to develop a data base regarding how the non-speech stimulus and the speech stimulus coded at brainstem during early developmental period. A total of fifty seven (57) subjects participated in the study. Subject’s age between 5 to 10 years were selected. All the participants were then divided into five groups.ABR and FFR were recorded using Biologic Navigator Pro evoked potential systems (Version-7.0). Results showed that there was no effect of repetition rate on latency and amplitude of click evoked ABR within group and across groups. Significant interaction was seen on the latency of speech evoked ABR and FFR within group, however it did not show significant interaction across groups. There was no significant interaction was seen on the amplitude of speech evoked ABR, but there was significant interaction on amplitude of FFR and F1 amplitude within group, but there was no significant interaction for F0 and F2. However there was no significant interaction for speech evoked ABR, FFR, F0, F1 & F2 latency & amplitude across groups. Developmental time course of speech encoding in the brainstem of neural maturation occur at the age of 5 years). Peripheral mechanism responsible for encoding temporal aspects of the acoustic signal appeared to be well developed in young listeners (4-5years) and this may be the reason for no difference was not noticed across age. Hence to study the temporal processing latency of speech evoked ABR and FFR waves should be considered. Amplitude of any wave is not a good parameter to study the rate effect.