Frequency discrimination limens and signal-to-noise ratios were determined for the sea catfish, Arius felis, using avoidance-conditioning techniques. The lowest frequency discrimination limens had values of about 2·5 % at 100 Hz. Other determinations were 3·5 % at 200 Hz, and 5 % at 400 Hz, but these values were significantly greater if the test frequencies were higher than the reference. Signal-to-noise ratios were 14 dB at 100 Hz, 18 dB at 200 Hz, and 24 dB at 400 Hz, with reference to the spectrum level of broad-band noise. These findings, and previous measurements of acuity, are discussed in relation to echolocation in Arius, which is known to involve sounds in the 100-200 Hz range.

© 1982 by Company of Biologists
1982
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