Neurobehavioral Correlates of Sound Communication in Anurans

Abstract

Animal sound communication involves a cooperative agreement between the sender and the receiver. This cooperation consists of a set of rules which constrains the sender to transmit only certain classes of sounds (in the appropriate context) in order to convey a meaningful message. The receiver, in turn, must use these rules to extract the “meaning” of the message. But the rules themselves are invisible, at least to a naive observer. They are either laid down in the nervous system through genetic control or else they must be learned and shaped by experience. Through experimental studies we can gain some insight into the rules that link the sender and receiver by identifying the physical features in an acoustic signal (i.e., its morphology) and the behavioral response which follows. In other words, we can “listen in” to their conversation and gradually learn the grammar which underlies their “foreign language”. Behavioral field studies aimed at this approach can be pursued quantitatively, because we have at our disposal a variety of calibrated instruments for recording and playback of animal sounds (e.g., condenser microphones, battery operated tape recorders, high-fidelity loudspeakers, and precision sound level meters). Furthermore, we can generate an endless variety of synthetic animal sounds by means of computer simulation or by use of dedicated analog and digital electrical instrumentation.