The perception of interleaved melodies

If the notes of two melodies whose pitch ranges do not overlap are interleaved in time so that successive tones come from the different melodies, the resulting sequence of tones is perceptually divided into groups that correspond to the two melodies. Such “melodic fission” demonstrates perceptual grouping based on pitch alone, and has been used extensively in music.Experiment I showed that the identification of interleaved pairs of familiar melodies is possible if their pitch ranges do not overlap, but difficult otherwise. A short-term recognition-memory paradigm (Expt II) showed that interleaving a “background” melody with an unfamiliar melody interferes with same-different judgments regardless of the separation of their pitch ranges, but that range separation attenuates the interference effect. When pitch ranges overlap, listeners can overcome the interference effect and recognize a familiar target melody if the target is prespecified, thereby permitting them to search actively for it (Expt III). But familiarity or prespecification of the interleaved background melody appears not to reduce its interfering effects on same-different judgments concerning unfamiliar target melodies (Expt IV).