ABSTRACT
Imaging studies demonstrate asymmetries in functional activation during speech and music processing (Binder et al., 1995; Szymanski, Rowley & Roberts, 1999; Zatorre, Evans, Meyer, & Gjedde, 1992; Zatorre, Meyer, Gjedde, & Evans, 1996). These asymmetries might result from different perceptual biases in the two hemispheres. Left hemisphere damage affects the discrimination of tone duration whereas right hemisphere damage affects pitch (Robin, Tranel, & Damasio, 1990). Asymmetrical effects of cortical damage have also been demonstrated in rats and monkeys (Fitch, Miller, & Tallal, 1997). The left hemisphere is more active when processing short-duration sounds (Belin et al., 1998). The left hemisphere has a perceptual bias for categorizing, i.e. naming stimuli, whereas the right hemisphere distinguishes fine gradations (Kosslyn, Gazzaniga, Galaburda, & Rabin, 1999).
