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Octave equivalence describes the perception that notes separated by a doubling in frequency sound similar. While the octave is used cross-culturally as a basis of pitch perception, experimental demonstration of the phenomenon has proved to be difficult. In past work, members of our group developed a three-range generalization paradigm that reliably demonstrated octave equivalence. In this study we replicate and expand on this previous work trying to answer three questions that help us understand the origins and potential cross-cultural significance of octave equivalence: (1) whether training with three ranges is strictly necessary or whether an easier-to-learn two-range task would be sufficient, (2) whether the task could demonstrate octave equivalence beyond neighbouring octaves, and (3) whether language skills and musical education impact the use of octave equivalence in this task. We conducted a large-sample study using variations of the original paradigm to answer these questions. Results found here suggest that the three-range discrimination task is indeed vital to demonstrating octave equivalence. In a two-range task, pitch height appears to be dominant over octave equivalence. Octave equivalence has an effect only when pitch height alone is not sufficient. Results also suggest that effects of octave equivalence are strongest between neighbouring octaves, and that tonal language and musical training have a positive effect on learning of discriminations but not on perception of octave equivalence during testing. We discuss these results considering their relevance to future research and to ongoing debates about the basis of octave equivalence perception.

Octave equivalence occurs when notes separated by an octave (a doubling in frequency) are judged as being perceptually similar. Considerable evidence points to the importance of the octave in music and speech. Yet, experimental demonstration of octave equivalence has been problematic. Using go/no-go operant discrimination and generalization, we studied octave equivalence in humans. In Experiment 1, we found that a procedure that failed to show octave equivalence in European starlings also failed in humans. In Experiment 2, we modified the procedure to control for the effects of pitch height perception by training participants in Octave 4 and testing in Octave 5. We found that the pattern of responding developed by discrimination training in Octave 4 generalized to Octave 5. We replicated and extended our findings in Experiment 3 by adding a transfer phase: Participants were trained with either the same or a reversed pattern of rewards in Octave 5. Participants transferred easily to the same pattern of reward in Octave 5 but struggled to learn the reversed pattern. We provided minimal instruction, presented no ordered sequences of notes, and used only sine-wave tones, but participants nonetheless constructed pitch chroma information from randomly ordered sequences of notes. Training in music weakly hindered octave generalization but moderately facilitated both positive and negative transfer.