The goal of Susan E. Allan's doctoral-dissertation research is to study the characteristics of sound signals that are important in communication. Such temporal properties as waveform periodicity, pulse repetition rate, and amplitude modulation are known to be important in acoustic communication of anurans (frogs and toads). Anurans are ideal animals to work with when studying acoustic communication. They communicate with small, well-defined repertoires used to attract mates, defend territories, and recognize species. Extensive work has been done on the sensitivity of the female green treefrog to temporal properties of the male's calls, but little experimental work has been done on the detection and behavioral responses of the male green treefrog to these same signals. Because males and females of some species are known to differ in behavioral and neurophysiological responses to a given signal, it is important to examine the significance of particular acoustic properties for males and females independently. Ms. Allan's research will focus on the sensitivity of the male green treefrog to the rate of amplitude modulation in the species' calls. This question will be investigated using three different experimental methods: laboratory evoked calling, field playback experiments, and a psychophysical method, reflex modification. Thus, the project will relate both behavioral and psychophysical results with the behavior of the animal in its natural environment.
