Sound Communication in Anurans (Frogs and Toads), Neuroethology of
There are almost 3,000 species of frogs and toads in the world today. Even though a number of different species may share a common breeding site, hybridization is relatively rare. The basis for this reproductive isolation resides in the males’ species-specific mating (advertisement) calls. Females are attracted selectively to calling males of their own species. These observations indicate that anurans are capable of precise acoustic recognition of complex sounds in a noisy environment, since the sound level of each calling male in a mixed chorus often is of the order of 100–110 decibels SPL (sound pressure level) at a distance of 1 meter. Furthermore, despite the small interaural distance between their eardrums and lack of external pinnae, they show remarkable accuracy in sound localization (which has been quantified by observation of female phonotac-tic approaches to playback of the male’s call.) Because of the fundamental role that vocal signals play in their lives and the fact that auditory discrimination and sound localization can be studied by means of acoustic playback of natural and synthetic calls (electronically or computer generated), anurans have proved to be a model system for neuroethological studies of sound communication.