Humans and other animals often communicate acoustically in noisy social environments. These environments present serious challenges to effective communication when multiple individuals signal simultaneously. A fundamental goal of auditory neuroscience is to understand how nervous systems group together the different sounds produced by one source in the presence of multiple competing sources. This research investigates auditory grouping in an animal model that communicates acoustically in large social groups and has a unique auditory system. The work uses behavioral assays and neural recordings to study how anurans (frogs and toads) use frequency cues to group the discrete sound elements comprising communication signals. Preliminary studies suggested that use of frequency cues by anurans is supported by two mechanisms, one similar to that of mammals and birds and one resulting from the unique physiology of anuran inner ears. Further study will investigate these mechanisms at various levels of the anuran auditory system. It is expected that low levels of the auditory system will use mechanisms similar to those that have been observed in other animals, but that there will be two distinct variations, again reflecting the anuran ears' unique physiology. At higher levels of the auditory system, a new mechanism is expected to manifest which combines frequency cues with temporal cues to produce a neural "readout" of the perceptual state of the animal. This research will contribute to a broader and more general understanding of how auditory systems perceive acoustic communication signals in noisy environments. Such data are essential for understanding the potential diversity of ways that evolution may solve common problems in diverse groups of animals. This basic biological knowledge, in turn, could one day benefit people with impaired hearing. The project also integrates research with the training and teaching of undergraduate and graduate students and additionally will foster an international collaboration.
