Process timing and its relation to the perception of tonal harmony

Abstract

Recent advances in auditory research suggest that gamma-band synchronization of frequency-specific cortical loci could be responsible for the integration of pure tones (harmonics) into harmonic complex tones. Thus far, evidence for such a mechanism has been revealed in neurophysiological studies, with little corroborative behavioral data. Using psychophysical techniques, we observed a rate- and time- specific response-time (RT) advantage for a sequence of target pips when the defining frequency of the target was a fractional multiple of an entrainer frequency. The effect was only observed when entrainer and target tone-pip sequences were presented at 33 pips per second (pps) and when the inter-stimulus interval (ISI) was approximately 100 milliseconds (ms). This evidence implicates the oscillatory gamma-band activity in the representation of harmonic complex tones and suggests that synchronization with precise temporal characteristics is important for their integration. A model is presented, which accounts for these findings in terms of fast resynchronization of relevant neuronal assemblies.