Distinguishing auditory and speech-specific perceptual deficits.

The ability to discriminate speech and nonspeech auditory stimuli was tested in a learning disabled child. The perception of speech stimuli was normal when the stimuli were presented in quiet but below normal when the stimuli were presented in noise. Although the perception of pure tone stimuli and environmental sounds was normal both in quiet and noise, the perception of nonspeech stimuli with rapid changes in acoustic information was impaired in noise. These findings illustrate the importance of relating performance for speech and complex nonspeech stimuli in investigating the basis of speech perceptual deficits. Whereas abnormal performance for speech stimuli coupled with normal performance for complex nonspeech stimuli argues for the existence of specialized speech processing mechanisms, abnormal performance for both types of stimuli, as was found in the present subject, argues for the existence of more generalized auditory processing mechanisms.