Electrophysiological and perceptual correlates of auditory processing in children with specific language impairment

Madhavi L Basu, Purdue University

Abstract

Perceptual and electrophysiological studies (using cortical evoked potentials) have shown that children with Specific language impairment (SLI) have difficulty processing sounds that are presented rapidly and/or having rapidly changing frequency components. However, it is not clear whether this deficit in temporal processing is specific to speech sounds or simply reflects a more general auditory processing problem. Also, it is not known if the temporal processing deficits are already present at the brainstem level. The aim of the current study was to evaluate if the perceptual difficulty is speech-specific; and if brainstem electrophysiological measures could reveal response behavior that maybe consistent with degradation of temporal processing. To this end, performance of children with SLI on speech and non speech sounds synthesized from sine-wave stimuli were compared. Frequency-following responses to tonal glides of varying trajectories and auditory brainstem responses to clicks presented at varying rates were also evaluated. Children with SLI did not show any differences in their performance on speech and non-speech categorical perception when compared to the controls. Children with SLI did not show clearly discernible phase-locking activity following the trajectory of frequency change, particularly at the faster sweep rate. They also showed longer latencies for waves III and V of the ABR than the controls and showed a greater prolongation of wave III at higher rates suggesting greater susceptibility to adaptation. Electrophysiological results suggest that children with SLI show greater degradation in phase-locking, to tonal glides of steeper trajectories and longer latencies than the controls possibly due to incomplete maturation of auditory pathway. While the electrophysiological results provide some support to the hypothesis that children with SLI might have temporal processing deficits, the perceptual results do not provide any support to the temporal processing or speech-specific deficit hypotheses. Further research on development of FFR in controls and children with SLI is recommended in order to obtain more information on the neuromaturational aspects of auditory processing at the brainstem level in both the groups.

Degree

Ph.D.

Advisors

Krishnan, Purdue University.

Subject Area

Audiology|Speech therapy

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