Auditory-visual integration: A comparison of neuropathy and developmental dyslexia

Abstract

Auditory neuropathy and developmental dyslexia have been previously associated with inferior perception of acoustic speech in noise. To probe the underlying mechanisms of these deficits, an audio-visual integration experiment was conducted to compare the speech perception abilities of reading-impaired subjects and auditory neuropathy patients (relative to controls). Natural acoustic speech stimuli that were white-noise masked at various intensities and accompanied by a video of the talker were presented to subjects. Neuropathy patients were expected to benefit from the pairing of visually presented articulatory cues and auditory CV stimuli, owing to the fact that their speech perception impairment reflects a peripheral auditory disorder. To the extent that developmental dyslexia reflects a general impairment of speech processing rather than a peripheral disorder of audition, it was hypothesized that reading-impaired subjects would not benefit from an introduction of visual cues. Current experimental data yielded a significant correlation between reading ability and dependence upon visual cues. Furthermore, under conditions where articulatory cues are matched with heavily masked CV stimuli, neuropathy patients and controls made more use of the visual cues than reading-impaired subjects. This may suggest that some forms of reading impairment stem from deficits of general speeach processing.