Superposition of Time-Interval Pitch Percepts

Abstract

Time-interval or repetition pitch may be considered to be the pitch percept associated with the interval between repeated portions of a stimulus waveform. A simple stimulus evoking this percept is a single, equal amplitude pulse pair. The pitch corresponds to the reciprocal of the interval between pulses. Repetition of the pulse pair, not necessarily periodic, increases the strength of the percept. Substitution of another waveform for each of the pulses can be expected to produce a similar percept. For example, wide-band noise delayed and added to itself produces a continuous stream of waveform segments correlated at the interval of the delay. Consider a stimulus consisting of wide-band noise that is multiply delayed and added to itself. Suppose that in general the delays are unequal. As a hypothesis, it is proposed that the over-all pitch percept is a superposition of time-interval pitch percepts associated with individual delays and combinations of delays. That is, the individual pitch percepts are apparent in the over-all percept. A series of pitch-matching and discrimination experiments has been undertaken, which strongly supports this hypothesis. More fundamentally, the results are consistent with a temporal rather than a spectral processing of pitch information for these stimuli.