Cortical Auditory-Evoked Potential and Behavioral Evidence for Differences in Auditory Processing between Good and Poor Readers.

Abstract

The relationship between auditory processing (AP) and reading is thought to be significant; however our understanding of this relationship is somewhat limited. Previous studies have investigated the relation between certain electrophysiological and behavioral measures of AP and reading abilities in children. This study attempts to further understand that relation. Differences in AP between good and poor readers were investigated using electrophysiological and behavioral measures. Thirty-two children (15 female) aged 9-11 yr were placed in either a good reader group or poor reader group, based on the scores of a nationally normed reading test in New Zealand. Children were initially tested using an automated behavioral measuring system that runs through a tablet computer known as "Feather Squadron." Following the administration of Feather Squadron, cortical auditory-evoked potentials (CAEPs) were recorded using a speech stimulus (/m/) with the HEARLab® Cortical Auditory Evoked Potential Analyzer. The children were evaluated on eight subsections of the Feather Squadron, and CAEP waveform peaks were visually identified and averaged. Separate Kruskal-Wallis analyses were performed for the behavioral and electrophysiological variables, with group (good versus poor readers) serving as the between-group independent variable and scores from the Feather Squadron AP tasks as well as CAEP latencies and amplitudes as dependent variables. After the children's AP status was determined, the entire group was further divided into three groups: typically developing, auditory processing disorder + reading difficulty (APD + RD), and RDs only. Statistical analyses were repeated for these subgroups. Poorer readers showed significantly worse scores than the good readers for the Tonal Pattern 1, Tonal Pattern 2, and Word Double Dichotic Right tasks. CAEP differences observed across groups indicated comorbid effects of RD and AP difficulties. N2 amplitude was significantly smaller for the poor readers. The current study found altered AP in poor readers using behavioral Feather Squadron measures and speech-evoked cortical potentials. These results provide further evidence that intact central auditory function is fundamental for reading development.