Relating Musical Contours: Extensions of a Theory for Contour

Cognitive psychologists and music theorists have, for many years, understood that human perception of pitch cannot simply be modelled along a single continuum from low to high.' Thus representational models for pitch perception have been developed by psychologists to reflect a number of related dimensions,2 among them the tendency of listeners familiar with Western tonal music to group octave-related pitches into equivalence classes. Nevertheless, in spite of this tendency, listeners are for the most part unable to recognize familiar melodies which have been distorted by octave displacement unless the melodic contour remains invariant. So important is the role of contour in the retention and recognition of well known melodies that even the size of the interval between successive pitches may be altered, and subjects will usually recognize the tune if the contour remains unaltered? Further, experimentation has shown that listeners frequently confuse a fugue subject with its tonal answer-that is, they identify the two as identical on the basis of their equivalent contours and diatonic scale types, despite the fact that their pitch contents differ. By extention to a non-tonal context, we may predict that listeners will be more likely to assume that non-equivalent sets belong to the same set class if their contours are the same. In fact, W. J. Dowling and D. S. Fugitani have offered experimental justification for the premise that listeners