Musicianship modulates octave illusion perception differently across stimulation frequencies

The octave illusion is a well-known auditory phenomenon elicited by binaural octave-separated tones alternating between the ears that engages parallel processing pathways for sound localization and pitch perception. It has mainly been studied using the central frequencies of the musical spectrum (e.g., 400-800 Hz). However, in a previous study, we measured a shift in the distribution of percepts reported by non-musicians at the upper and lower boundaries of the musical spectrum, suggesting a reduced pitch perception accuracy. This study now aims to determine if musical training, which is known to improve pitch perception, affects the relative distribution of percepts across frequencies. 24 non-musicians and 19 professional musicians listened to the illusion evoked by pairs of frequencies ranging from 40 to 80 Hz to 2000-4000 Hz, and selected which percept they heard (octave, simple, complex). In non-musicians, the results replicate the previously reported shift in the distribution of percepts at higher and lower frequencies, but no such perceptual shift was measured in musicians. At lower frequencies, musicians were more likely than non-musicians to report the octave percept and less likely to report simple percepts. For the classic paradigm frequencies (400-800 Hz), musicians were more likely to report a complex percept that more closely matched the true pattern of stimulation used to elicit the illusion. In conclusion, musical training seems to preserve pitch representation at the lower boundaries of the musical spectrum, and musicians seem to have a more consistent distribution of percept elicited by the illusion across different frequencies.