The Psychophysics of Harmony Perception: Harmony is a Three-Tone Phenomenon

Abstract

In line with musical common sense (but contrary to the century-old tradition of musical psychophysics), we show that harmony is an inherently three-tone phenomenon. Previous attempts at explaining the affective response to major/minor chords and resolved/unresolved chords on the basis of the summation of interval dissonance have been notably unsuccessful, but consideration of the relative size of the intervals contained in triads leads directly to solutions to these historical problems. At the heart of our model is Leonard Meyer's idea from 1956 concerning intervallic equidistance - i.e., the perception of tension inherent to any three-tone combination that has two intervals of equivalent size (e.g., the augmented chord). By including the effects of the upper partials, a psychophysical explanation of the perceived sonority of the triads (major>minor>diminished>augmented) and the affective valence of major and minor chords is easily achieved. We conclude that the perceptual regularities of traditional diatonic harmony are neither due to the summation of interval effects nor simply arbitrary, learned cultural artifacts, but rather that harmony has a psychophysical basis dependent on three-tone combinations. THE psychophysical study of music has an honorable history going back at least to Helmholtz (1877). Particularly since the 1960s and the widespread use of electronic techniques to create and measure musical tones with great precision, the perception of two-tone intervals and the influence of upper partials on the perception of intervals have been rigorously examined, and several important insights gained. Some of the successes of this reductionist scientific approach to the perception of music will be reviewed below, but a discussion of the science of music must begin with a statement of the complete failure thus far to account for the core phenomena of diatonic harmony on psychophysical principles. Most significantly, the fact that some chords sound stable, final and resolved, while others sound unstable, tense and unresolved cannot be explained solely on the basis of the summation of interval dissonance among tones and their upper partials. Moreover, although the positive and negative affective valence of major and minor chords is salient both to young children and to adults from diverse cultures, this also has not been explained. As a consequence of the simultaneous ability to explain the basics of interval perception (and therefore the emergence of diatonic and pentatonic musical scales worldwide) and yet the inability to explain the perception of even the simplest of three-tone harmonies, there is a widespread (if often implicit) acknowledgement that harmony perception may be a result of the learning of the arbitrary tone patterns commonly used within the so-called Western idiom, with little acoustic rationale for these patterns other than the consonance of certain intervals. THREE-TONE PSYCHOPHYSICS