[The thresholds of discriminating the duration of frequency-modulated signals by cats behaving freely]

Threshold values of duration if frequency modulated signals (sweeps) were measured under the free behaviour conditions in cats. Modulation of the sweeps was carried out linearly in a diapason of 2-100 ms with both increasing and decreasing frequency and embedded in tone stimuli with central frequency of 2.5 kHz and total duration of 0.5 s. The sweeping rate was the same in all cases and equal to 1.2 kHz/s. While training, animals had to discriminate "short" (2 ms) signals (heard by a human as clicks) and "long" (100 ms) signals (with well expressed frequency change when hearing). Different durations being used in experiments, at the sweeping duration of 30 ms cats qualified signals as "short" and "long" ones with equal probabilities. The results are similar to those obtained for humans in spite of significant difference in frequency resolution ability for animals and humans.