Name:Marise van Zyl

School/Affiliation:Stanford University, CCRMA

Co-Authors:Takako Fujioka

Virtual or In-person:In-person

Abstract:

Previous research has shown that spatial information in sound is processed in the brain preattentively. Specifically, stimulus changes in room acoustics (with a different reverberation) or sound source location (with a different binaural cue) elicit mismatch negativity (MMN). However, it is unclear how these two auditory-feature processes interact with each other, if at all. In this study, we examine MMN and P3a by using an oddball paradigm with complex tones as standard stimuli, originating from a central location and within a given reverberation condition - either big or small. Three deviant types - reverb, location (60 degrees right), and both reverb and location - were presented randomly each at 8.3%. We also used complex tones with either 300 Hz or 2000 Hz fundamental frequency to separate interaural time difference (ITD) and interaural level difference (ILD) binaural cues. We tested two alternative hypotheses: (1) reverberation and sound location are processed independently, predicting the summation of responses for reverb and location deviants would be similar to the response to the double deviant, (2) reverberation and location processing could interact with each other, predicting that the double deviant response is significantly different from two single deviant summation. Results followed the second hypothesis for MMN amplitude. Furthermore, ANOVA showed a significant interaction between frequency and deviant types because of stronger negativity for 300Hz than 2000 Hz. No interactions were found for P3a. Our data suggest that a reverberation change with binaural cue is processed quite similarly to the binaural cue itself at the preattentive level, indicating the integration of the room acoustic information into spatial object separation.