Frequency and practice interactions in frequency discrimination

Abstract

Differences between human infants and adults in frequency discrimination resemble differences between untrained and trained adults: frequency difference limens (FDL's) tend to be relatively worse for infants and untrained adults at low frequencies [L. W. Olsho, Inf. Behav. Dev. 7, 27–35 (1984)]. To demonstrate directly that the effect of training in frequency discrimination depends on frequency, the course of improvement in frequency discrimination was examined in adults at 500, 1000, and 4000 Hz. Stimuli were pure tones presented at a 40‐dB sensation level. A two‐alternative forced‐choice procedure was used, and FDL was tracked using a one‐up, two‐down adaptive procedure. Four subjects completed 200–250 trials of training at each frequency. For these subjects not only was initial FDL much higher relative to final FDL at the two lower frequencies, but tracking width decreased progressively with increasing frequency. Four additional subjects were tested for a total of 20 h each to make certain that asymptotic performance was reached. The final FDL's obtained by these listeners were similar to those reported by other investigators [e.g., C. C. Weir et al., J. Acoust. Soc. Am. 61, 178–184 (1977)], and the same practice effects were observed as in the first group. [Work supported by NIH.]