Perception of spectrally and temporally complex sounds by the goldfish (Carassius auratus).

Behavioral studies on complex sound perception in goldfish were carried out in order to help determine what, if any, differences exist between the sense of hearing of fishes and other vertebrates. A stimulus generalization paradigm was used with classical conditioning in three experiments to determine: (1) the perceptual relations between a pure tone and harmonic complexes having a fundamental frequency equal to that of the tone; (2) the combined effects on perception of pulse repetition rate and spectral envelope; and (3) whether goldfish can be shown to identify a complex source when presented simultaneously with another complex source. Experiment 1 showed that the perceptions of tones and harmonic complexes differ profoundly even for the cases in which they have common periodicities and frequency components. Experiment 2 demonstrated that pulse repetition rate and spectral location simultaneously control behavior, and that repetition rate exerts behavioral control independent of spectral location. Experiment 3 indicates that goldfish did not 'hear out' or analyze a complex target source within a mixture of complex sources. In general, goldfish appear to be aware of multiple acoustic dimensions of complex sounds, suggesting both pitch-like and timbre-like perceptual dimensions. These results do not permit a qualitative distinction between the sense of hearing of goldfish and that of other vertebrates.