Publications

Abstract

Rhythm and vocal production learning are building blocks of human music and speech. Vocal learning has been hypothesized as a prerequisite for rhythmic capacities. Yet, no mammalian vocal learner but humans have shown the capacity to flexibly and spontaneously discriminate rhythmic patterns. Here we tested untrained rhythm discrimination in a mammalian vocal learning species, the harbour seal (Phoca vitulina). Twenty wild-born seals were exposed to music-like playbacks of conspecific call sequences varying in basic rhythmic properties. These properties were called length, sequence regularity, and overall tempo. All three features significantly influenced seals' reaction (number of looks and their duration), demonstrating spontaneous rhythm discrimination in a vocal learning mammal. This finding supports the rhythm–vocal learning hypothesis and showcases pinnipeds as promising models for comparative research on rhythmic phylogenies.

Abstract

The auditory scene is a mental representation of individual sounds extracted from the summed sound waveform reaching the ears of the listeners. Musical contexts represent particularly complex cases of auditory scenes. In such a scenario, melody may be seen as the main object moving on a background represented by the accompaniment. Both melody and accompaniment vary in time according to harmonic rules, forming a typical texture with melody in the most prominent, salient voice. In the present sparse acquisition functional magnetic resonance imaging study, we investigated the interplay between melody and accompaniment in trained pianists, by observing the activation responses elicited by processing: (1) melody placed in the upper and lower texture voices, leading to, respectively, a higher and lower auditory salience; (2) harmonic violations occurring in either the melody, the accompaniment, or both. The results indicated that the neural activation elicited by the processing of polyphonic compositions in expert musicians depends upon the upper versus lower position of the melodic line in the texture, and showed an overall greater activation for the harmonic processing of melody over accompaniment. Both these two predominant effects were characterized by the involvement of the posterior cingulate cortex and precuneus, among other associative brain regions. We discuss the prominent role of the posterior medial cortex in the processing of melodic and harmonic information in the auditory stream, and propose to frame this processing in relation to the cognitive construction of complex multimodal sensory imagery scenes.