Robert Capranica

  • Evoked Vocal Response of the Bullfrog

    A Study of Communication and Sound

    Robert Capranica

    “Field observations... have suggested that sound communication probably plays a significant role in the lives of most anurans (frogs and toads) and that most species can apparently discriminate certain sounds made by members of their own species from those made by members of other species.”

    “... research might provide experimental evidence for the naturalist's hypothesis concerning the species specificity of anuran vocalizations and, at the same time, might relate the auditory capabilities of the anuran to the coding of these sounds in his nervous system.”

    These are the theories that gave rise to this unprecedented experimental investigation of the behavioral capabilities of bullfrogs to discriminate between controlled acoustic stimuli, thus revealing the basis for their selective detection of the mating call of their own species, and of the close relationship of this behavioral research to recent electrophysiological findings in the bullfrog's auditory nervous system. Few definitive studies of sound communication in anurans have been made because of difficulties encountered with previous experimental techniques, thus this monograph serves to clarify previous misunderstandings and to offer new information in this field, and to provide the basis for studies of sound communication in other species. The book reviews the behavioral and physiological evidence of vocalization and hearing in frogs and toads and offers a detailed report of research on the vocal responses of laboratory colonies of bullfrogs to the acoustic presentation of natural and synthetic mating calls. The research concentrates mainly on the stimulus parameters of these sounds which are necessary in evoking calling from the laboratory animals.

    The monograph will prove most valuable to naturalists concerned with the significance and specificity of animal sounds, behaviorists interested in techniques for studying vocalization and hearing in animals, and neurophysiologists concerned with the correlation of behavior to the coding of acoustic stimuli in the nervous system. Electrical engineers and communication specialists will find a wealth of information in this unique study.

    • Hardcover $10.00