Auditory Brainstem Responses in Dyslexia: Comparison between Acoustic Click and Verbal Stimulus Events

Abstract

This study examined the use of auditory brainstem response (ABR) by classic clicks and verbal stimuli in young dyslexic adults to identify latency abnormalities. Subjects included 10 dyslexic adults and 10 age-, sex-, IQ-, education-, and hearing sensitivity-matched normal subjects. Both groups had normal auditory status. Measurements included the absolute latencies of waves I through V; the interpeak latencies I-III, III-V, and I-V elicited by acoustic click; and the negative peak latencies of A and B waves, as well as the interpeak latencies of A-B elicited by the verbal stimulus "ma," created on a digital speech synthesizer. The measured latencies and interpeak latencies in response to both clicks and verbal stimuli were found delayed in eight dyslexic subjects, although they did not reach the level of significant difference. However, two dyslexic subjects had significantly delayed peak and interpeak latencies elicited by verbal stimuli. There are dyslexic subjects who may have abnormalities in acoustic representation of a speech sound as low as the auditory brainstem, as elicited by the verbal stimulus "ma."