Fundamental pitch discrimination for monotic and dichotic two‐tone complexes

Abstract

Pitch discrimination for the fundamental frequency of a harmonic two‐tone complex was investigated. The stimuli were either monotic, with both tones presented to a single ear, or dichotic, with one tone presented to each ear. An up—down two‐alternative forced‐choice procedure was employed. In each block of trials, seven differences in fundamental frequency around a fundamental frequency of 275 Hz were tested. The procedure was designed to minimize the pitch discrimination cue arising from the partials. The difference in fundamental frequency necessary for 75% correct discrimination (defined as Δf0) was measured as a function of the harmonic number (5–9) and duration (15–250 msec) of the complexes. Two general trends emerged from these data. First, as the duration of the complex tone decreased below 250 msec, performance deteriorated. The rank order of the Δf0's correlated well with duration, but the data were not characterized by a simple reciprocal relationship between Δf0 and stimulus duration. Second, except at the shortest duration tested, discriminability in the dichotic condition was less sensitive than that for the monotic condition. These results are in qualitative agreement with expectations of the pitch saliency of complex tones. [This research was supported by a National Institutes of Health research grant awarded to ASU.]