Developmental Psychology 1996, Vol. 32. No. 6, 1039-1050 Copyright 1996 by the American Psychological Association, Inc. O012-1649/96/S3.0O Children's Discrimination of Melodic Intervals E. Glenn Schellenberg University of Windsor Sandra E. Trehub University of Toronto Adults and 6-year-old children were tested on their discrimination of pure-tone sequences as a func- tion of the simplicity of the frequency ratios between tones in the sequences. Listeners were required to detect either changes from intervals (combinations of 2 tones) with simple frequency ratios to those with more complex ratios or changes from intervals with complex frequency ratios to those with simpler ratios. In Experiment 1, adults performed better on changes from simple ratios (2:1, 3:2, or 4:3) to more complex ratios (15:8, 32:15, or 45:32) than on the reverse changes. In Experi- ment 2, 6-year-olds who had never taken music lessons exhibited a similar pattern of performance. The observed asymmetries in performance imply that intervals with simple frequency ratios are naturally more coherent than are those with more complex ratios. The diversity of musical styles across cultures and even within a culture implies that knowledge of particular styles of music is largely acquired through exposure. Indeed, music from foreign (non-Western) cultures often sounds strange and sometimes unpleasant to listeners who have only been exposed to Western musical structures. This situation does not preclude the possi- bility that some structural properties are shared by most if not all musical styles, or that some aspects of musical understanding are biologically based (Blacking, 1992). In the present article, we consider whether some aspects of Western music processing appear spontaneously and relatively early in development be- cause they are based on inherent good form (Garner, 1974; Trehub & Unyk, 1991) or coherence (Bharucha & Pryor, 1986). Such processing strategies if evident would likely be re- flected in structural regularities across musical cultures. It is possible that some combinations of tones may simply be more coherent, perhaps even more pleasing (i.e., consonant), than others. We use coherence to refer to the ease with which a group of tones combine to form a single, potentially recogniz- able, percept (Bharucha & Pryor, 1986). Combinations of two tones (i.e., pairs of tones) are known as intervals, either melodic, consisting of two successive tones, or harmonic, consisting of two simultaneous tones. An interval is generally characterized by the pitch distance between its component tones (e.g., num- ber of semitones) or by its frequency ratio, which relates the frequency of one component tone to that of the other. For ex- ample, tones of 200 Hz and 100 Hz have a frequency ratio of 2:1 (i.e., 12 semitones or an octave). Because musical pitch is perceived relationally (Attneave & Olson, 1971), the interval between tones of 300 Hz and 150 Hz is perceptually equivalent This research was supported by the Natural Sciences and Engineering Research Council of Canada, and by a Grant-in-Aid of Research from Sigma Xi, The Scientific Research Society. Correspondence concerning this article should be addressed to E. Glenn Schellenberg, Department of Psychology, University of Windsor, Windsor, Ontario, Canada N9B 3P4, or to Sandra E. Trehub, University of Toronto, Erindale Campus, Mississauga, Ontario, Canada L5L 1C6. Electronic mail may be sent to E. Glenn Schellenberg via Internet to schelle@uwindsor.ca. to that between tones of 200 and 100 Hz, both having a fre- quency ratio of 2:1. It follows that musical tunes maintain their invariance over changes in their initial tone provided the in- tervals (frequency ratios or numbers of semitones) between tones remain constant. When listening to music, then, each tone is perceived in relation to previously heard tones. In comparison with speech, the relational and nonreferential nature of music perception generates greater demands on work- ing memory. The limits of working memory likely account for the use of scales (a finite set of tones or pitches in music) and the occurrence of five to seven different tones per octave (Dowling & Harwood, 1986; Handel, 1989). The Western ma- jor scale, for example, comprises seven tones: do, re, mi, fa, sol, la, and ti. One consequence of the use of a scale is a small set of possible intervals among its component tones. Other biological influences on the structure of scales could favor some intervals over others, contributing to "a base of innate abilities and ten- dencies" (Sloboda, 1985, p. 194) from which music perception and performance abilities develop. Indeed, beginning with Py- thagoras (Winnington-Ingram, 1980), numerous theorists have considered intervals with simple (i.e., small integer) ratios such as 2:1 and 3:2 to be more natural and consonant than other intervals (e.g., Bernstein, 1976; Kolinski, 1967; Roederer, 1979). These theorists have also considered scales whose in- tervals form simple frequency ratios to be more natural than other scales (see Burns & Ward, 1982). Simple frequency ratios could be relatively coherent because of their presence in naturally occurring sounds (Terhardt, 1974, 1978,1984). Most sounds in our environment, including those of speech and music, consist of several simultaneous pure tones (sine waves). For example, the sound produced by a single key on a piano is a multitone complex consisting of a number of simultaneous pure tones, the frequency of each being an integer multiple of the lowest component (or fundamental frequency). Thus, the lowest component of the note A (below middle C) is 220 Hz; successive components (harmonics or overtones) have frequencies of 440 Hz (two times 220 Hz), 660 Hz (three times 220 Hz), 880 Hz (four times 220 Hz), and so on. Accordingly, intervals between the simultaneous components of such com- plex tones have simple frequency ratios (2:1 between 440 Hz 1039