Human brain specialization for phonetic attention

THE effects of auditory selective attention on event related potentials (ER Ps) to speech sounds were examined in subjects attending to vowel-consonant -vowels (VCVs) in one ear while ignoring VCVs in the opposite ear. In one c ondition, subjects discriminated phonetic changes in the VC, CV, or both fo rmant-transition regions. In another condition, they discriminated equally difficult intensity changes in the same VCV regions. Attention-related nega tive difference waves showed enhanced early and late components (Nd-e and N d-l) during phoneme-discrimination conditions. Hemispheric asymmetries deve loped only during the Nd-l and were more pronounced during phoneme discrimi nation. The results suggest that auditory areas of both hemispheres are spe cialized for phonetic analysis, with hemispherically specialized mechanisms engaged primarily during the final stages of phoneme processing. NeuroRepo rt 10:1605-1608 (C) 1999 Lippincott Williams & Wilkins.