Investigating the influence of auditory streaming cues on binaural pitch fusion

Binaural pitch fusion occurs when dichotic signals eliciting a different pitch are perceived as one sound. Previously, Oh et al. (ASA 2018) investigated the effects of auditory streaming cues on binaural fusion using a modification of the ABA streaming paradigm. A dichotic stimulus (fixed tone at frequency fref in the reference ear and variable frequency in the contralateral ear) was presented at alternating intervals with a “capture” tone at fref. Binaural fusion frequency range decreased, suggesting competition of the capture with the variable frequency tone for fusion. The present study added more capture tones, allowing for a galloping percept, and varied the inter-stimulus interval (ISI), both hypothesized to decrease binaural fusion by increasing salience of the capture tone. The dichotic stimulus was presented alternating with two or three repetitions of the capture tone at fref for triplet and quadruplet paradigms, respectively. ISIs of 40 or 80ms were used. Participants reported whether they perceived galloping or two streams. Preliminary data from 5 normal-hearing listeners suggest reductions in binaural fusion range with the triplet and quadruplet paradigms, and longer ISI, compared to the original paradigm. These findings indicate that auditory grouping cues may potentially reduce binaural fusion. [Research funded by NIH/NIDCD R01DC013307.]