Perceptual limits of octave harmony

Abstract

Three subjects were monaurally presented with dyads of frequency‐modulated pure tones approximately 1 octave apart. The tones, with carrier frequencies FL and FH, were heard in a background of pink noise and at a low sensation level, so that they were completely resolvable by the subjects' peripheral auditory filters. In experiments 1 and 2, subjects judged on each trial which of two dyads was inharmonic (FH≠2.FL); the relative mistuning of the inharmonic dyad [(FH − 2.FL)/2.FL] was varied independently of FL and could be either positive or negative; FL was fixed within trials in one experiment, and varied within trials (from about 8%–20%) in the other experiment. In both experiments, performance monotonically worsened when FL was increased from 300–2000 Hz; in addition, negative mistunings were better identified as inharmonicities than positive mistunings. In a third experiment, a 4I‐2AFC procedure was used to assess the detectability of changes in FH irrespective of their effect on the perception of harmonicity. Performances were not the same function of FL as in the other two experiments, and were much better for high FL values. Thus it is concluded that detection of inharmonicity (experiments 1 and 2) was limited by factors other than those responsible for fine pitch discriminations. These results also have implications with respect to the origin of human listeners' melodic octave templates.