Abnormal speech sound representation in persistent developmental stuttering.

OBJECTIVES To determine whether adults with persistent developmental stuttering (PDS) have auditory perceptual deficits. METHODS The authors compared the mismatch negativity (MMN) event-related brain potential elicited to simple tone (frequency and duration) and phonetic contrasts in a sample of PDS subjects with that recorded in a sample of paired fluent control subjects. RESULTS Subjects with developmental stuttering had normal MMN to simple tone contrasts but a significant supratemporal left-lateralized enhancement of this electrophysiologic response to phonetic contrasts. In addition, the enhanced MMN correlated positively with speech disfluency as self-rated by the subjects. CONCLUSIONS Individuals with persistent developmental stuttering have abnormal permanent traces for speech sounds, and their abnormal speech sound representation may underlie their speech disorder. The link between abnormal speech neural traces of the auditory cortex and speech disfluency supports the relevance of speech perception mechanisms to speech production.