Effects of long-term musical training on across-stream timing sensitivity

In general, it is more difficult to judge the timing of sounds in a sequence when they are in perceptually segregated streams than in a single stream. This study examined timing judgment performance among individuals with different musical training histories to ask whether this difficulty could be reduced by training to compare component timings across streams. Forty-five Japanese participants listened to two sequences: one consisting of four repetitions of low (A), high (B), low (A), and silent (-) patterns with regular intervals, and another in which every B tone was delayed. They were asked to indicate which of the two sequences, presented in random order, contained the delay. The frequency separation between A and B tones was 0, 1, 2, or 3 octaves. Each participant’s 75%-correct delay thresholds, estimated by a logistic mixed-effect model, were analyzed against their Musical Training score from the Goldsmiths Musical Sophistication Index (Gold-MSI). Thresholds increased with greater frequency separation, which likely induced auditory stream segregation. Higher musical training scores were associated with lower thresholds, which was particularly evident in the 2 and 3 octave conditions. These findings suggest that instrumental training enhances timing sensitivity across streams and/or reduces segregation driven by spectral separation.