Relation between Absolute Threshold and Duration-of-Tone Pulses in the Bottlenosed Porpoise

Results of a study of absolute threshold and duration-of-tone pulses in the bottlenosed porpoise indicated that the animal, in detecting pure-tone stimuli, integrated the acoustic energy in essentially the same way as humans. Pure-tone thresholds were determined at 0.25, 1, 4, 20, 45, and 100 kHz for a wide range of pulse durations. Least-squares fits to the data yielded time constants that were in general agreement with those obtained in experiments with humans. The data for very short pulses at 20 and 40 kHz indicated the presence of critical-frequency bands, for which rough estimates were obtained.