Abstract: Adults and 6-year-old children were tested on their discrimination of  pure-tone sequences as a function 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 Experiment 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.