Effect of Phase on the Quality of a Two-Component Tone

Listener responses to monaurally presented two-component stimuli (a 250-cps tone and its octave, at various intensities and phase relations) reveal striking individual differences and unexpected patterns. With certain pairs of these stimuli, that stimulus which is consistently judged higher in pitch (or louder or purer) by one subject is just as consistently judged lower (or softer or less pure) by another. When the intensity of one of the stimulus components and the phase angle between the components are held constant, reversals of phase of the entire stimulus become discriminable as soon as the intensity of the second component is increased a little above threshold. With certain combinations, as the second component is further increased, phase discrimination for one subject reaches a maximum, decreases to chance, and then increases again. For another subject under the same set of conditions, phase discrimination does not fail, but rather, monotonically increases. No single explanation accounts for the subjects' patterns of responses and for their sensory experiences. Rather, it seems that two or more of several suggested mechanisms are involved.