Perceiving a change in a nonperceived pitch

Abstract

Listeners were presented with 300-ms ‘‘chords’’ of five synchronous pure tones, followed after a 0.5–8-s silence by a single pure tone. The frequencies of each chord’s components were selected randomly, but spaced by intervals of between 6 and 10 semitones. In one condition (‘‘up/down’’), the single tone following a chord was 1 semitone higher or lower than one of the chord’s three intermediate components; on each trial, the corresponding component was selected randomly and the task was to indicate the direction in which its pitch changed. In another condition (‘‘present/absent’’), the single tone following a chord was either identical to one of the three intermediate components or halfway in frequency between two components; the task was to indicate if the single tone was present in the chord or not. Performance was much better in the up/down condition than in the present/absent condition, even though the opposite trend was predictable for an ideal ‘‘analytic’’ listener. Ten listeners reported that, in the up/down condition, they could often perceive the appropriate pitch change without having heard out the relevant component of the chord. These results provide strong evidence for the existence of pitch change detectors in the auditory system.