title: Frogs Exploit Statistical Regularities in Noisy Acoustic Scenes to Solve Cocktail-Party-like Problems.
abstract: Noise is a ubiquitous source of errors in all forms of communication [1]. Noise-induced errors in speech communication, for example, make it difficult for humans to converse in noisy social settings, a challenge aptly named the "cocktail party problem" [2]. Many nonhuman animals also communicate acoustically in noisy social groups and thus face biologically analogous problems [3]. However, we know little about how the perceptual systems of receivers are evolutionarily adapted to avoid the costs of noise-induced errors in communication. In this study of Cope's gray treefrog (Hyla chrysoscelis; Hylidae), we investigated whether receivers exploit a potential statistical regularity present in noisy acoustic scenes to reduce errors in signal recognition and discrimination. We developed an anatomical/physiological model of the peripheral auditory system to show that temporal correlation in amplitude fluctuations across the frequency spectrum ("comodulation") [4-6] is a feature of the noise generated by large breeding choruses of sexually advertising males. In four psychophysical experiments, we investigated whether females exploit comodulation in background noise to mitigate noise-induced errors in evolutionarily critical mate-choice decisions. Subjects experienced fewer errors in recognizing conspecific calls and in selecting the calls of high-quality mates in the presence of simulated chorus noise that was comodulated. These data show unequivocally, and for the first time, that exploiting statistical regularities present in noisy acoustic scenes is an important biological strategy for solving cocktail-party-like problems in nonhuman animal communication.
authors.affiliation: Department of Ecology, Evolution, and Behavior, University of Minnesota, Saint Paul, MN 55108, USA. Electronic address: lee33@stolaf.edu.
authors.forename: Norman
authors.initials: N
authors.lastname: Lee
authors.affiliation: Department of Ecology, Evolution, and Behavior, University of Minnesota, Saint Paul, MN 55108, USA; Department of Fisheries, Wildlife, and Conservation Biology, University of Minnesota, Saint Paul, MN 55108, USA.
authors.forename: Jessica L
authors.initials: JL
authors.lastname: Ward
authors.affiliation: Department of Ecology, Evolution, and Behavior, University of Minnesota, Saint Paul, MN 55108, USA.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Vélez
authors.affiliation: Department of Psychology, University of Minnesota, Minneapolis, MN 55455, USA.
authors.forename: Christophe
authors.initials: C
authors.lastname: Micheyl
authors.affiliation: Department of Ecology, Evolution, and Behavior, University of Minnesota, Saint Paul, MN 55108, USA; Graduate Program in Neuroscience, University of Minnesota, Minneapolis, MN 55455, USA.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Bee
mesh_terms: D000818:Animals; D001001:Anura / Q000502:physiology*; D005260:Female; D008297:Male; D010470:Perceptual Masking; D011601:Psychophysics; D013017:Sound Localization; D014828:Vocalization, Animal
keywords: acoustic communication; auditory masking; auditory scene analysis; cocktail party problem; comodulation masking release; mate choice; natural scene statistics; noise; sexual selection; species recognition