Spatial hearing in Cope's gray treefrog: I. Open and closed loop experiments on sound localization in the presence and absence of noise

Michael S. Caldwell, Mark A. Bee

Research output: Contribution to journalArticlepeer-review

18 Scopus citations

Abstract

The ability to reliably locate sound sources is critical to anurans, which navigate acoustically complex breeding choruses when choosing mates. Yet, the factors influencing sound localization performance in frogs remain largely unexplored. We applied two complementary methodologies, open and closed loop playback trials, to identify influences on localization abilities in Cope's gray treefrog, Hyla chrysoscelis. We examined localization acuity and phonotaxis behavior of females in response to advertisement calls presented from 12 azimuthal angles, at two signal levels, in the presence and absence of noise, and at two noise levels. Orientation responses were consistent with precise localization of sound sources, rather than binary discrimination between sources on either side of the body (lateralization). Frogs were unable to discriminate between sounds arriving from forward and rearward directions, and accurate localization was limited to forward sound presentation angles. Within this region, sound presentation angle had little effect on localization acuity. The presence of noise and low signal-to-noise ratios also did not strongly impair localization ability in open loop trials, but females exhibited reduced phonotaxis performance consistent with impaired localization during closed loop trials. We discuss these results in light of previous work on spatial hearing in anurans.

Original languageEnglish (US)
Pages (from-to)265-284
Number of pages20
JournalJournal of Comparative Physiology A: Neuroethology, Sensory, Neural, and Behavioral Physiology
Volume200
Issue number4
DOIs
StatePublished - Apr 2014

Bibliographical note

Funding Information:
Acknowledgments We thank nate Buerkle and Betsy linehan-Skillings for help testing frogs, Anastasia Johns for help with video analyses, Sandra Tekmen and Jessica Ward for logistical support, and norman lee, Jessica Ward, and two anonymous reviewers for helpful feedback on earlier drafts of the manuscript. All procedures followed the guide for the Care and Use of laboratory Animals and were approved by the University of Minnesota’s Institutional Animal Care and Use Committee (#0809A46721 and #1202A10178). This work was supported by the national Institute on Deafness and Other Communication Disorders (r01 DC009582).

Keywords

  • Anura
  • Communication
  • Ear
  • Sound localization
  • Source segregation

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