A bidimensional model of pitch in the recognition of melodies

Pitch can be conceptualized as a bidimensional quantity, reflecting both the overall pitch level of a tone (tone height) and its position in the octave (tone chroma). Though such a conceptualization has been well supported for perception of a single tone, it has been argued that the dimension of tone chroma is irrelevant in melodic perception. In the current study, melodies were subjected to structural transformations designed to evaluate the effects of interval magnitude, contour, tone height, and tone chroma. In two transformations, the component tones of a melody were displaced by octave intervals, either preserving or violating the pattern of changes in pitch direction (melodic contour). Replicating previous work, when contour was violated perception of the melody was severely disrupted. In contrast, when contour was preserved the melodies were identified as accurately as the untransformed melodies. In other transformations, a variety of forms of contour information were preserved, while eliminating information for absolute pitch and interval magnitude. The level of performance on all such transformations fell between the levels observed in the other two conditions. These results suggest that the bidimensional model of pitch is applicable to recognition of melodies as well as single tones. Moreover, the results argue that contour, as well as interval magnitude, is providing essential information for melodic perception.