PERCEPTION OF COMPLEX SOUNDS BY THE GREEN TREEFROG, HYLA-CINEREA - ENVELOPE AND FINE-STRUCTURE CUES

1. The envelope periodicity of communication signals is an important f eature distinguishing advertisement and aggressive calls for the green treefrog (Hyla cinerea). Envelope periodicity, a cue for periodicity pitch perception in humans, is affected by the fine-structure of the s ignal, a cue for timbre perception in humans. The present study examin ed perception of two acoustic features affecting waveform fine-structu re - harmonic structure and phase structure - in male green treefrogs. 2. We analyzed evoked vocal responses of male green treefrogs living in laboratory arenas to playbacks of digitally-generated signals resem bling either conspecific advertisement or aggressive calls in their fi rst harmonic periodicity. Systematic changes in the harmonic structure of these signals were achieved by varying the harmonic relations betw een frequency components in the signals, and changes in phase structur e were achieved by varying the starting phases of harmonically-related components. 3. Calling was significantly influenced by the first harm onic periodicity of the signals. Males vocalized more to signals with the periodicity of the advertisement than the aggressive call. There w ere no differences in response to harmonic and inharmonic signals with similar spectral content. Phase structure did not significantly influ ence vocal responses. 4. These results suggest that the fine-structure (''timbre'') of complex acoustic signals is not a significant feature guiding behavior tested using a communication response in this specie s.