On measuring the frequency-difference limen for short tones

Abstract

The standard deviation of the distribution of matching frequencies in a two-interval pitch-matching experiment and the width of the psychometric function in a two-interval frequency-discrimination experiment both provide measures of the frequency-difference limen (DL). We compared DLs as measured by these two methods for tones of short duration, using all nine pairings of durations 12, 25, and 50 msec, at nominal frequencies of 200, 342,584, and 1000 Hz. We found that the two experiments gave qualitatively different results. In frequency discrimination, the DL decreased as the duration of either the standard or the comparison tone increased, as expected from statistical decision theory in one dimension. In pitch matching, the DL was smallest whenever the standard and comparison tones had equal durations. To explain this dichotomy, we suggest that, for tones of short duration, a pitch-matching experiment permits a multidimensional comparison of two tones, but that a frequency-discrimination experiment forces a comparison along a single perceptual dimension.