Further Studies of Masking in the Greater Horseshoe Bat, Rhinolophus ferrumequinum

Abstract

Psychophysical studies have shown that the auditory system of man and other mammals seem to act like a series of bandpass filters which, with the exception of the lowest frequencies, increase linearly with log frequency. This author (Long, 1977) obtained an indirect measure of these bandwidths (critical ratios) using a classically conditioned response to shock and found that, while the critical ratios from Rhinolophus ferrumequinum were consistent with those from other mammals below 75 kHz, they decreased dramatically near the reference frequency. At that time it was not possible to specify the relation of these results to other modifications in these bats (see Neuweiler and Pollak, this volume). Further research was conducted using essentially the same method except that the noise was generated by multiplying 9.9 kHz low-pass noise by a pure tone giving rise to 19.8 kHz bandwidth 18 dB SPL/Hz noise centered at the frequency of the tone.