Transfer of learning across durations and ears in auditory frequency discrimination

Frequency-discrimination thresholds (FDTs) for 1-kHz tone pips with durations of 40, 100, and 200 msec were measured in the left and right ears of 10 normal-hearing listeners, before and after six 2-h frequency-discrimination training sessions involving, exclusively, the 200-msec duration and the right ear In the trained ear, highly significant improvements in FDTs were observed at all durations. Further inspection of the data suggested complete generalization between 200 and 100 msec, but not at 40 msec. Post-training FDTs were not found to differ between the two ears for the two untrained durations, but proved significantly smaller in the right (trained) than in the left (untrained) ear at the trained (200-msec) duration only. A control experiment involving 10 additional subjects allowed us to establish the absence of intrinsic differences in pretraining FDTs between the right and left ears. Overall, these findings indicate that frequency-discrimination learning generalizes widely across stimulus durations and across ears, but that part of the improvement is specific to the range of durations and to the ear used in training.