Perceived similarity of exact and inexact transpositions.

The purpose of this study was to investigate the perceived similarity between a melody and the exact and inexact transpositions of that melody. Exact transpositions, which preserve the interval structure of the original melody, were formed by manipulating the variables key-distance and pitch-distance. Inexact transpositions, having a different interval structure than the original melody, were created by altering one tone of the exact transpositions. Two types of alteration, retaining the contour of the original melody, were used: (1) a chromatic alteration of one tone fitting the key of the original melody; (2) a diatonic alteration of one tone fitting the key of the transposed melody. The coding model of Deutsch and Feroe (1981) was used as a qualitative predictor of the perceived similarity. The resulting predictions were tested using a paired-comparison paradigm. Results indicate that both pitch-distance and alteration explain a significant part of the variance, whereas key-distance does not contribute significantly. It was also found that exact transpositions are perceptually more similar to the original melody than inexact transpositions, and that chromatically altered transpositions are perceptually more similar to the original melody than diatonically altered transpositions. These results are broadly in accordance with the applied coding model.