Hemisphere differences in event-related potentials (ERPS) to monaural presentations of simple speech sounds.
The aim of the present study was to compare ERPs over the left and right hemispheres to monaural consonant-vowel (CV) syllables. It was predicted that, if the contralateral auditory representation is stronger than the ipsilateral one, then ERPs over the left hemisphere should be larger for right-ear stimulus input. Furthermore, if the hemispheres differ in efficiency in processing of speech sounds, then ERPs recorded at any given site should vary as a function of the ear to which the sound is presented. Twelve right-handed subjects participated. The CV-syllables used were /Ba/ and /Pa/ with 15 presentations of each syllable to each ear in a randomized order. EEG was recorded from F3, Fz, and F4 with linked ears as reference. The results showed no significant asymmetry in the ERP-leads. N1- and N2-amplitudes were, however, larger at Fz than at F3 and F4, and N1-latency was shorter for right-ear presentations, which also interacted with the /Pa/-syllable presentations. P3-latency was longer to the /Pa/-syllable compared to the /Ba/-syllable, while N4-latency was longer to the /Ba/-syllable. N4-amplitude was more negative for the /Pa/-syllable presented to the left ear. The results are discussed in terms of phonemic differences between the unvoiced /Pa/ and voiced /Ba/, and early versus late stages of processing. The results are also seen in relation to ear differences in dichotic listening.
Kvale
G
G
Department of Biological and Medical Psychology, University of Bergen, Norway.
Hugdahl
K
K
Nordby
H
H
Hammerborg
D
D
D000328:Adult; D001288:Attention / Q000502:physiology*; D004007:Dichotic Listening Tests; D004292:Dominance, Cerebral / Q000502:physiology*; D004569:Electroencephalography / Q000295:instrumentation*; D005072:Evoked Potentials, Auditory / Q000502:physiology; D005625:Frontal Lobe / Q000502:physiology; D006801:Humans; D008297:Male; D010700:Phonetics; D011930:Reaction Time / Q000502:physiology; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation*; D013067:Speech Perception / Q000502:physiology*