Sound reception in the Brazilian cicada Fidicina rana Walk

Sound reception in the Brazilian cicada Fidicina rana has been studied by recording the electrical activity in the auditory nerve in response to various sound stimuli. The highest sensitivity to pure tones is in the frequency range of 6-9 kHz. A considerable and rapid adaptation occurs. The response to trains of clicks consists of a series of compound action potentials. At repetition rates above loo/sec. this response also shows adaptation. The response to the natural continuous song of the cicada is not very different from the response to trains of artificially produced clicks. In the two other types of natural song the adaptation of the auditory response is circumvented. Thus the response to the ‘zeep’ call (during which the intensity of consecutive cficks increases) consists of a series of compound action potentials of about the same amplitude, and the response to the distress call consists of a short burst of action potentials for each burst of clicks. It is suggested that these songs therefore constitute very effective methods of intraspecific signalling.