Examining the auditory cortex response to musical stimuli with differences in timbre and reverberation

Abstract

In a previous functional magnetic resonance imaging (fMRI) study by the authors, the addition of reverberation was shown to degrade the cortical auditory response to musical stimuli. This degradation may occur since reverberation blurs the frequency content of the stimuli in time, making it more difficult for the brain to distinguish between distinct auditory objects. The current study aims to further establish the auditory response to reverberant stimuli by investigating if higher-order frequency content (timbre) affects the auditory cortex’s sensitivity to reverberation. Using an anechoic solo-instrumental trumpet motif, a sine-trumpet musical stimulus was generated by removing the harmonic content from the played notes while maintaining the attack of the instrument and rhythm of the musical passage. Auralizations of both motifs were created from eight simulated room conditions with reverberation times ranging from 0.0-7.2 s. Participants were recruited to rate the auralizations in terms of overall preference, perceived reverberance, and perceived clarity. Subsequently, the participants listened to a subset of the solo-instrumental and sine-trumpet auralizations in an MRI machine. Contrasts between the motifs and room acoustic conditions were analyzed to confirm the sensitivity of the auditory cortex to reverberation, as well as investigate the possible interaction effect between reverberation and timbre.