Sound Processing in Real-World Environments

Abstract

Acoustic communication in a frog's natural environment is challenging because sound is susceptible to distortion during transmission and to masking by chorus noise. At present, knowledge of how anurans solve these communication problems is limited. This chapter describes the many interesting behavioral and physiological questions that remain unresolved. In particular, behavioral evaluations of detection, recognition, or localization have been made extensively, but mostly in quiet backgrounds. Further studies are much needed to gain insight into the auditory performances in the presence of multiple competing sounds (resembling the frog's natural listening environments). The extent of involvement of other sensory cues in localization and recognition of mates also needs to be reexamined. Future experiments should examine frog's behaviors either in total darkness or in an optically uniform arena. Another issue needing further study is whether frogs perform auditory grouping and source segregation, that is, whether they hear different callers within a chorus as separate perceptual objects or whether the entire auditory scene is perceived as a single object as in insects (Wendler 1989; Helversen and Helversen 1995; Helversen et al. 2001). This issue must be resolved before the search for neuronal correlates of stream segregation and auditory grouping can begin.