Communication is a fundamental aspect of the biology of most animals. Acoustic signals are often used to communicate in groups or social aggregations, in which multiple individuals signal within a receiver’s hearing range. Consequently, receivers face challenges related to acoustic interference and auditory masking that are not unlike the so-called "cocktail party problem," which refers to the difficulty we humans have understanding speech in noisy social settings. Despite a general interest in acoustic signaling in groups, however, biologists have so far devoted little attention toward uncovering the diversity of ways nonhuman animals may be evolutionarily adapted to solve their own cocktail-party-like problems. Among the best known examples of "animal cocktail parties" are choruses of singing frogs, in which loud acoustic signals are produced in large groups in the context of reproduction.

Our long-term goal is to understand the functional consequences of communicating in noisy environments and the neural and perceptual mechanisms that allow listeners to mitigate these consequences. We use behavioral, biomechanical, and neurophysiological methods to investigate how the auditory systems of North American treefrogs exploit spectral, temporal, and spatial cues to perceive mating calls in noisy choruses. Typical frog calls have amplitudes of 80-90 dB SPL (at 1 m), which compares with the amplitude of an alarm clock or garbage disposal. Breeding choruses of frogs commonly range in size from dozens to hundreds of calling males, usually of multiple species. In order to reproduce, female frogs must detect, recognize, localize, and discriminate among the calls of individual males in the chorus. The central hypothesis we are testing is that frogs possess low-level, “data-driven” mechanisms that function to segregate vocal signals from overlapping signals and from the general din of a noisy social environment. The rationale for this research is that by gaining a better understanding of the mechanisms for sound source perception in frogs and other animals, we will not only learn about the sensory and perceptual mechanisms that make animal communication possible, we will also contribute to a body of knowledge that could lead to the development of improved biologically-inspired technologies for acoustic signal processing in noise.

This body of research is currently supported by a grant from the National Science Foundation (IOS-2022253) and has been supported in the past by grants from the National Science Foundation (IOS-1452831) and the National Institute on Deafness and Other Communication Disorders (R01DC009582, R03DC008396).

You can read about this work in the following reviews:

Bee MA, Christensen-Dalsgaard J (2016) Sound source localization and segregation with internally coupled ears: The treefrog model. Biological Cybernetics, 110, 271-290.

Bee MA (2015) Treefrogs as animal models for research on auditory scene analysis and the cocktail party problem. International Journal of Psychophysics, 95, 216–237

Schwartz JJ and Bee MA (2013) Anuran acoustic signal production in noisy environments. In: Brumm H (ed) Animal Communication and Noise. Springer: New York, pp 91-132.

Vélez A, Schwartz JJ, and Bee MA (2013) Anuran acoustic signal perception in noisy environments. In: Brumm H (ed) Animal Communication and Noise. Springer: New York, pp 133-185.

Bee MA (2012) Sound source perception in anuran amphibians. Current Opinion in Neurobiology, 22, 301-310.