Long lasting musical training modifies language processing: a Dichotic Fused Word Test study

Musical training modifies neural areas associated with both music and language and enhances speech perception and discrimination by engaging the right hemisphere regions classically associated with music processing. On these bases we hypothesized that participants with extended musical training could have reduced left-hemisphere dominance for speech. In order to verify this hypothesis, two groups of right-handed individuals, one with long-term musical training and one with no musical training, participated to a Dichotic Fused Word Test consisting in the simultaneous presentation of different pairs of rhyming words and pseudo-words, one to the left ear and one to the right one. Participants typically show a greater number of reports of the right ear input than of the left one. This effect, called right ear advantage (REA), reflects left-hemisphere dominance for speech processing. In our study, we expected that musicians had a reduced dichotic listening REA for linguistic stimuli. The main result of this study was the attenuation, and in some cases the complete suppression, of the dichotic effect in musicians, since most of them perceived both words, simultaneously. This finding suggests that both hemispheres may have similar verbal competence and contribute to speech processing in parallel. This contrasts with the normal brain organization in which hemispheres cooperate but are engaged in different analysis of speech. The "two words" perception also extended to pseudo-words. Thus, musical training, by shaping the language circuits, could produce the enhancement of bilateral processing of stimuli with linguistic characteristics (i.e. phonetics) independently of semantics