From air oscillations to music and speech:: Functional magnetic resonance imaging evidence for fine-tuned neural networks in audition

In the auditory modality, music and speech have high informational and emotional value for human beings. However, the degree of the functional specialization of the cortical and subcortical areas in encoding music and speech sounds is not yet known. We investigated the functional specialization of the human auditory system in processing music and speech by functional magnetic resonance imaging recordings. During recordings, the subjects were presented with saxophone sounds and pseudowords /ba:ba/ with comparable acoustical content. Our data show that areas encoding music and speech sounds differ in the temporal and frontal lobes. Moreover, slight variations in sound pitch and duration activated thalamic structures differentially. However, this was the case with speech sounds only while no such effect was evidenced with music sounds. Thus, our data reveal the existence of a functional specialization of the human brain in accurately representing sound information at both cortical and subcortical areas. They indicate that not only the sound category (speech/music) but also the sound parameter (pitch/duration) can be selectively encoded.