Comparative frequency selectivity in fishes: Simultaneously and forward-masked psychophysical tuning curves

Abstract

Behavioral methods were used to determine psychophysical tuning curves for three teleostean fish species (Notopterus chitala, Adioryx xantherythrus, and Osteoglossum bicirrhosum) for 300- and 500-Hz signals. Simultaneous masking techniques revealed that 300-Hz curves were similar for all species, with peak masking occurring when the frequency of the masker equaled 300 Hz. In contrast, there were considerable interspecific differences in simultaneously masked 500-Hz curves. The 500-Hz curve for Adioryx was a broadly tuned, V-shaped function with peak masking occurring in the frequency region of the signal, whereas the curve for Notopterus was a sharply tuned, multipeaked function with peak masking occurring for both 500- and 300-Hz maskers. Comparisons of tuning curves obtained with both forward and simultaneous masking techniques for Notopterus revealed little or no difference between 300-Hz curves, but substantial differences between the 500-Hz curves. These results suggest that there are interspecific and frequency-dependent differences in the frequency selective processes of fish auditory systems.