E. Glenn Schellenberg
Dept. of Psychol., Cornell Univ., Ithaca, NY 14853
Sandra E. Trehub
Univ. of Toronto, Erindale College, Mississauga, ON L5L 1C6, Canada
The effect of frequency ratio complexity on the discrimination of changes to sequential tonal patterns was examined. Patterns consisted of two alternating pure tones (ABABA). Subjects heard a repeating background pattern (the standard pattern) presented in transposition (same frequency ratios between tones, different absolute frequencies), and were asked to identify when a contrasting pattern (different frequency ratios, different absolute frequencies) was substituted. Changes were significantly easier to identify when the component tones of the background pattern were related by small integer frequency ratios (3:2 or 4:3) and those of the contrasting pattern were related by more complex ratios (45:32) than when the situation was reversed. The effect did not extend to cases in which the relative differences in ratio complexity were reduced (3:2 vs 8:5 or 4:3 vs 5:4). A multiple regression analysis of the combined data sets showed that frequency ratio complexity of component tones in both the standard (background) and contrasting patterns made independent contributions in predicting these results. These findings cannot be explained by notions such as critical bandwidth. Moreover, the present test procedure may be a more sensitive measure of effects of tonal consonance and dissonance than others previously used.