Despite the importance of perceptually separating signals from background noise, we still know little about how nonhuman animals solve this problem. Dip listening, an ability to catch meaningful 'acoustic glimpses' of a target signal when fluctuating background noise levels momentarily drop, constitutes one possible solution. Amplitude-modulated noises, however, can sometimes impair signal recognition through a process known as modulation masking. We asked whether fluctuating noise simulating a breeding chorus affects the ability of female green treefrogs (Hyla cinerea) to recognize male advertisement calls. Our analysis of recordings of the sounds of green treefrog choruses reveal that their levels fluctuate primarily at rates below 10 Hz. In laboratory phonotaxis tests, we found no evidence for dip listening or modulation masking. Mean signal recognition thresholds in the presence of fluctuating chorus-like noises were never statistically different from those in the presence of a non-fluctuating control. An analysis of statistical effects sizes indicates that masker fluctuation rates, and the presence versus absence of fluctuations, had negligible effects on subject behavior. Together, our results suggest that females listening in natural settings should receive no benefits, nor experience any additional constraints, as a result of level fluctuations in the soundscape of green treefrog choruses.
|Original language||English (US)|
|Number of pages||14|
|Journal||Journal of Comparative Physiology A: Neuroethology, Sensory, Neural, and Behavioral Physiology|
|State||Published - Dec 2012|
Bibliographical noteFunding Information:
Acknowledgments All procedures for collecting, handling, and testing animals were approved by the University of Minnesota’s Institutional Animal Care and Use Committee (IACUC No. 0809A46721, November 2008). We thank N. Buerkle, M. Caldwell, B. Chicoine, J. Cook, C. Espegard, S. Feingold, N. Hein, K. Heino, J. Henly, S. Hinrichs, M. Johnson, J. Kleinschmidt, B. Linehan-Skillings, J. Mertz, V. Nityananda, C. Nguyen, S. Peterson, A. Rapacz Van-Neuren, and especially S. Tekmen for help testing frogs, R. Sparrow for access to frog breeding sites, and M. Caldwell, B. Pettit, K. Schrode, and J. Ward for feedback on earlier versions of the manuscript. This work was supported by a UMN Graduate School Thesis Research Grant and a Dayton-Wilkie Fellowship to A. Vélez and by NSF IOS 0842759 and NIDCD 5R01DC009582 to M. Bee.
- Cocktail party problem
- Dip listening
- Green treefrog
- Hyla cinerea
- Modulation masking