Neural Underpinnings of the Continuity Illusion in Musicians

The continuity illusion occurs when a sound is perceived as continuous through noise-filled interruptions and has been indexed neurophysiologically as reduced auditory theta band (4-8 Hz) power and phase-locking at the interruption boundaries. Here, we examined the behavioural and neurophysiological differences between musicians (n = 16) and nonmusicians (n = 16) as they listened to trisyllabic words and classical music with noise interruptions. Our aim was to assess two competing hypotheses: (H₁) because of their enhanced ability to detect acoustic gaps, musicians are less likely to perceive continuity and will therefore exhibit increased theta power/phase-locking at interruption boundaries compared to nonmusicians. Alternatively, (H₂) musicians are more likely to perceive continuity through an enhanced ability to utilize contextual cues to fill in missing information. This top-down influence should be demonstrated by reduced theta power/phase-locking in musicians. On each trial, participants reported whether a noise-interrupted music or speech stimulus sounded continuous or interrupted. Behaviorally, musicians and nonmusicians had similar rates of perceived continuity for music and speech, except musicians exhibited significantly greater continuity to speech at the shortest noise interruption. The oscillatory results demonstrated that relative to nonmusicians, musicians had weaker theta phase-locking to the interruption boundaries in both music and speech, supporting H₂. Musicians also exhibited enhanced alpha (8-13 Hz) and beta (14-30 Hz) power for both music and speech relative to nonmusicians, possibly reflecting inhibitory processes. We conclude that musicians exhibit enhanced auditory-motor inhibition to noise interruptions in both music and speech and infer this is due to their enhanced ability to utilize contextual cues.