The Neuroethology of Vocal Communication: Perception and Cognition

Abstract

In its most common sense, acoustic communication occurs between animals, but in special cases it may occur within individual animals in the context of autocommunication. Communication can be described as an information exchange that alters the behavior of the communicating animals. Acoustic communication signals (typically vocalizations) are shaped by the physics of the sound-producing organs, the physical media they traverse, and the physics of the receptor organs (Bass and Clark, Chapter 2; Fitch and Hauser, Chapter 3; Ryan and Kime, Chapter 5). Vocal communication signals are also shaped by the perceptual mechanisms of the receiver, by the proximate behavioral states of the senders and receivers (Boughman and Moss, Chapter 4; Yamaguchi and Kelley, Chapter 6), and by the evolutionary history of the senders and receivers, most often in the context of sexual selection. The information in vocal signals is represented by nonrandom acoustic variation that may either form discrete categories or fall along graded continua. Likewise, vocal signals may be perceived as members of discrete categories or along graded continua. Whether graded or discrete, animals must account for the statistical variation in vocal signals as they are produced, transmitted, and perceived. Ultimately, this means that acoustic behaviors are constrained by the natural variation in communication signals. The wide diversity of behavioral constraints makes exploration of the neural mechanisms of acoustic communication both exciting and daunting. On one hand, one of the grand challenges in neurobiology has been the application of mechanistic analysis to perceptual and cognitive components of brain function, and the neuroethology of acoustic communication provides a logical and rigorous approach to such problems. At the same time, however, proper treatment of the mechanisms of acoustic communication requires a neural analysis that is sensitive to multiple levels of biological organization along with information-theoretic analyses that capture variations in behavior and signal acoustics. Despite good progress on many