Pattern Specificity in the Effect of Prior Δf on Auditory Stream Segregation

摘要

During repeating sequences of low (A) and high (B) tones, perception of two separate streams (" streaming") increases with greater frequency separation (Δf) between the A and B tones; in contrast, a prior context with large Δ f results in less streaming during a subsequent test pattern. The purpose of the present study was to investigate what aspects of the context pattern are necessary for this context effect to occur. Simply changing the B-tone frequency without an alternating A tone present was not sufficient to cause the effect of prior Δ f, but rather a melodic change between A and B tones was necessary. We further investigated the extent to which the context and test patterns needed to have similar rhythms (xxx-xxx-) and melodies (up-down-flat-up-down), and found that a maximal prior-Δ f effect occurred when the rhythmic patterns of the context and test were similar, regardless of the melodic structure. Thus, the effect of prior Δ f on streaming depended on the presence of (1) at least one melodic change in the context, and (2) similar rhythmic patterns in the context and test.