Behavioral assessment of acoustic parameters relevant to signal recognition and preference in a vocal fish

Acoustic signal recognition depends on the receiver's processing of the phy sical attributes of a sound. This study takes advantage of the simple commu nication sounds produced by plainfin midshipman fish to examine effects of signal variation on call recognition and preference. Nesting male midshipma n generate both long duration (>1 min) sinusoidal-like ''hums'' and short d uration "grunts." The hums of neighboring males often overlap, creating bea t waveforms. Presentation of humlike, single tone stimuli, but not grunts o r noise, elicited robust attraction (phonotaxis) by gravid females. In two- choice tests, females differentiated and chose between acoustic signals tha t differed in duration, frequency, amplitude, and fine temporal content. Fr equency preferences were temperature dependent, in accord with the known te mperature dependence of hum fundamental frequency. Concurrent hums were sim ulated with two-tone beat stimuli, either presented from a single speaker o r produced more naturally by interference between adjacent sources. Whereas certain single-source beats reduced stimulus attractiveness, beats which r esolved into unmodulated tones at their sources did not affect preference. These results demonstrate that phonotactic assessment of stimulus relevance can be applied in a teleost fish, and that multiple signal parameters can affect receiver response in a vertebrate with relatively simple communicati on signals. (C) 1998 Acoustical Society of America. [S0001-4966(98)02412-6] .