Abstract:

Echolocation clicks (N~30 000) were collected from an Atlantic bottlenose dolphin (Tursiops truncatus) performing object discrimination tasks. Eight categories of clicks were identified using the spectral conformation and relative position of -3- and -10-dB peaks. A counter-propagation network utilizing 16 inputs, 50 hidden units, and 8 output units, was trained to classify clicks using the same spectral variables. The network classified novel clicks with 92% success. Additional echolocation clicks (N~24 000) from two other dolphins were submitted to the network for classification. Classified echolocation clicks were analyzed for animal-specific differences, changes in predominant click type within click trains, and task-related specificity. Differences in animal and task performance may influence click type and click-train length.