title: Ambient noise causes independent changes in distinct spectro-temporal features of echolocation calls in horseshoe bats.
abstract: One of the most efficient mechanisms to optimize signal-to-noise ratios is the Lombard effect - an involuntary rise in call amplitude due to ambient noise. It is often accompanied by changes in the spectro-temporal composition of calls. We examined the effects of broadband-filtered noise on the spectro-temporal composition of horseshoe bat echolocation calls, which consist of a constant-frequency component and initial and terminal frequency-modulated components. We found that the frequency-modulated components became larger for almost all noise conditions, whereas the bandwidth of the constant-frequency component increased only when broadband-filtered noise was centered on or above the calls' dominant or fundamental frequency. This indicates that ambient noise independently modifies the associated acoustic parameters of the Lombard effect, such as spectro-temporal features, and could significantly affect the bat's ability to detect and locate targets. Our findings may be of significance in evaluating the impact of environmental noise on echolocation behavior in bats.
authors.affiliation: Department of Integrative Biology and Physiology, University of California Los Angeles, Los Angeles, CA 90095-7246, USA Department of Animal Physiology, Institute of Neurobiology, Tübingen University, 72076 Tübingen, Germany steffen.hage@uni-tuebingen.de.
authors.forename: Steffen R
authors.initials: SR
authors.lastname: Hage
authors.affiliation: Department of Integrative Biology and Physiology, University of California Los Angeles, Los Angeles, CA 90095-7246, USA Jilin Key Laboratory of Animal Resource Conservation and Utilization, Northeast Normal University, Changchun 130024, Jilin, China.
authors.forename: Tinglei
authors.initials: T
authors.lastname: Jiang
authors.affiliation: Department of Integrative Biology and Physiology, University of California Los Angeles, Los Angeles, CA 90095-7246, USA Autism and Developmental Disabilities Research Group, Stanford University, Stanford, CA 94305-5719, USA.
authors.forename: Sean W
authors.initials: SW
authors.lastname: Berquist
authors.affiliation: Jilin Key Laboratory of Animal Resource Conservation and Utilization, Northeast Normal University, Changchun 130024, Jilin, China.
authors.forename: Jiang
authors.initials: J
authors.lastname: Feng
authors.affiliation: Department of Integrative Biology and Physiology, University of California Los Angeles, Los Angeles, CA 90095-7246, USA Neurosensing and Bionavigation Research Center, Doshisha University, Kyotanabe, Kyoto 610-0321, Japan.
authors.forename: Walter
authors.initials: W
authors.lastname: Metzner
mesh_terms: D000161:Acoustic Stimulation; D000818:Animals; D002685:Chiroptera / Q000502:physiology*; D004455:Echolocation / Q000502:physiology*; D009622:Noise; D010470:Perceptual Masking; D059629:Signal-To-Noise Ratio; D014828:Vocalization, Animal / Q000502:physiology*
keywords: Acoustic communication; Audio-vocal integration; Bat echolocation; Lombard effect; Signal masking; Vocalization