Fig. 3.

Spectrograms of three examples of copy treatments where animals called back with the same whistle; sampling rate: 48,000 Hz, FFT length: 1,024, Hanning window function. Playback stimuli are labeled (PB) and the average similarities of the whistles produced by the animals to the playback are given; high similarity whistles (vocal reply) are highlighted (*). If the time between the playback and the response is greater than a few seconds, arrows have been inserted indicating the actual time.