Lombard effect revisited: ambient noise induces independent shifts in call frequency and amplitude

Abstract

Event Abstract Back to Event Lombard effect revisited: ambient noise induces independent shifts in call frequency and amplitude Steffen Hage1, 2, Tinglei Jiang1, 3, Sean Berquist1, Jiang Feng3 and Walter Metzner1, 4* 1 University of California, Los Angeles, IBP, United States 2 University of Tuebingen, Animal Physiology, Germany 3 Northeast Normal University, Jilin Key Laboratory of Animal Resource Conservation and Utilization, China 4 Doshisha University, Neurosensing and Bionavigation Research Center, Japan Any transmission of signals between sender and receiver faces the challenge of being subjected to masking by noise. For acoustic signals, for example, animals have evolved several strategies that aid in increasing the signal to noise ratio, thus facilitating signal transmission. One of the most efficient mechanisms is the so-called Lombard effect, i.e., the involuntary rise in call amplitude and frequency in response to masking ambient noise. This reflex was first described in human communication a century ago and has since been also found in several species of birds, frogs and various mammals. Most studies, however, focused on noise-dependent changes in call amplitude and less on shifts in frequency. It is therefore still largely unknown how the adaptive changes in call amplitude relate to frequency shifts and how the underlying mechanisms are linked. It is also unknown if auditory feedback from the changing vocal output is needed to drive the Lombard effect. In the present study, we examined the Lombard effect in a highly vocal mammal, echolocating horseshoe bats. We analyzed how bandpass-filtered noise (bandwidth 20 kHz) affected their echolocation behavior when the noise was centered at different frequencies within the hearing range of these bats. We found a robust increase in call amplitude only when the bandpass-filtered noise was centered on the dominant frequency component of the bats’ calls. The rises in call amplitude increased with increasing noise amplitude. In contrast, the frequency of the bats’ calls always increased regardless of the frequency the bandpass-filtered noise was centered on. Both, rises in amplitude and frequency were extremely fast and already occurred in the first call uttered after noise onset. This suggests that the bats did not need auditory feedback of their own voice to control the rises in amplitude and frequency observed in the Lombard effect. Finally, the different effects that varying the frequency bands within which the bandpass-filtered noise was presented had on amplitude and frequency shifts imply that the neural circuits underlying the rises in call amplitude and frequency of the Lombard effect differ and involve different frequency bands. These results therefore shed new light on a fundamental mechanism of vocal motor control. Keywords: auditory feedback, Echolocation, horseshoe bat, vocal motor control Conference: Tenth International Congress of Neuroethology, College Park. Maryland USA, United States, 5 Aug - 10 Aug, 2012. Presentation Type: Poster Presentation (see alternatives below as well) Topic: Sensory: Audition Citation: Hage S, Jiang T, Berquist S, Feng J and Metzner W (2012). Lombard effect revisited: ambient noise induces independent shifts in call frequency and amplitude. Conference Abstract: Tenth International Congress of Neuroethology. doi: 10.3389/conf.fnbeh.2012.27.00398 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 01 May 2012; Published Online: 07 Jul 2012. * Correspondence: Dr. Walter Metzner, University of California, Los Angeles, IBP, Los Angeles, CA, 90095, United States, metzner@ucla.edu Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Steffen Hage Tinglei Jiang Sean Berquist Jiang Feng Walter Metzner Google Steffen Hage Tinglei Jiang Sean Berquist Jiang Feng Walter Metzner Google Scholar Steffen Hage Tinglei Jiang Sean Berquist Jiang Feng Walter Metzner PubMed Steffen Hage Tinglei Jiang Sean Berquist Jiang Feng Walter Metzner Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.