The perception of a melody is invariant to the absolute properties of its constituting notes, but depends on the relation between them—the melody's relative pitch profile. In fact, a melody's “Gestalt” is recognized regardless of the instrument or key used to play it. Pitch processing in general is assumed to occur at the level of the auditory cortex. However, it is unknown whether early auditory regions are able to encode pitch sequences integrated over time (i.e., melodies) and whether the resulting representations are invariant to specific keys. Here, we presented participants different melodies composed of the same 4 harmonic pitches during functional magnetic resonance imaging recordings. Additionally, we played the same melodies transposed in different keys and on different instruments. We found that melodies were invariantly represented by their blood oxygen level–dependent activation patterns in primary and secondary auditory cortices across instruments, and also across keys. Our findings extend common hierarchical models of auditory processing by showing that melodies are encoded independent of absolute pitch and based on their relative pitch profile as early as the primary auditory cortex.
Friday, November 15, 2013
Where musical melodies are represented in our brains.
Here is a fascinating piece by Schindler et al. (open access) showing that musical melodies, or ‘gestalts’ are encoded at very early stages of our auditory processing and are constant through changes of key signature and type of instrument playing.