Electrophysiological correlates of timbre imagery and perception

Abstract

The primary objective of the present study was to verify whether the differences in imagined timbre are reflected by the event-related potentials (ERPs). It was verified the hypotheses that imagining of sounds, varying in spectral characteristics of timbre, influence the amplitude of the late positive component (LPC), associated with auditory imagery-related processes. It was also verified whether the manipulation of the perceived timbre corresponds to the amplitude fluctuations of the auditory evoked potentials (AEPs) N1 and P2. Also, it was expected that the amplitudes of the LPC, N1 and P2 components depend on musical expertise.Musicians and non-musicians took part in two experiments, each of which involved timbre manipulation in term of one parameter of the sound spectrum – spectral centroid or spectral irregularity. Each experiment consisted of auditory perception task followed by auditory imagery training and auditory imagery task.The present study showed that differences in perceived timbre associated with spectral centroid and spectral irregularity are reflected by fluctuations in the amplitude of the N1 and P2 potentials. Perceived differences in spectral centroid are sufficiently distinctive that generation of auditory images of sounds differing in this property induces changes in the amplitude of the late positive component (LPC), recorded during auditory imagery. This means that the LPC is sensitive to changes in the timbre of the imagined sound. Musicians are more accurate in performing auditory imagery task related to timbre than non-musicians. However, musical expertise does not affect the amplitude of the N1, P2 and LPC potentials.