DOCSLIB.ORG

Accuracy of an Acoustic Location System for Monitoring the Position of Duetting Songbirds in Tropical Forest

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Accuracy of an Acoustic Location System for Monitoring the Position of Duetting Songbirds in Tropical Forest University of Windsor Scholarship at UWindsor Biological Sciences Publications Department of Biological Sciences 2006 Accuracy of an acoustic location system for monitoring the position of duetting songbirds in tropical forest Daniel J. Mennill University of Windsor John M. Burt Kurt M. Fristrup Sandra L. Vehrencamp Follow this and additional works at: https://scholar.uwindsor.ca/biologypub Part of the Biology Commons Recommended Citation Mennill, Daniel J.; Burt, John M.; Fristrup, Kurt M.; and Vehrencamp, Sandra L., "Accuracy of an acoustic location system for monitoring the position of duetting songbirds in tropical forest" (2006). Journal of the Acoustical Society of America, 119, 5, 2832-2839. https://scholar.uwindsor.ca/biologypub/1030 This Article is brought to you for free and open access by the Department of Biological Sciences at Scholarship at UWindsor. It has been accepted for inclusion in Biological Sciences Publications by an authorized administrator of Scholarship at UWindsor. For more information, please contact [email protected]. Accuracy of an acoustic location system for monitoring the position of duetting songbirds in tropical forest Daniel J. Mennill, John M. Burt, Kurt M. Fristrup, and Sandra L. Vehrencamp Citation: The Journal of the Acoustical Society of America 119, 2832 (2006); doi: 10.1121/1.2184988 View online: https://doi.org/10.1121/1.2184988 View Table of Contents: http://asa.scitation.org/toc/jas/119/5 Published by the Acoustical Society of America Articles you may be interested in Acoustic localization of antbirds in a Mexican rainforest using a wireless sensor network The Journal of the Acoustical Society of America 128, 182 (2010); 10.1121/1.3425729 Short- and long-term changes in right whale calling behavior: The potential effects of noise on acoustic communication The Journal of the Acoustical Society of America 122, 3725 (2007); 10.1121/1.2799904 Manatee position estimation by passive acoustic localization The Journal of the Acoustical Society of America 121, 2049 (2007); 10.1121/1.2532210 Measuring the free field acoustic impedance and absorption coefficient of sound absorbing materials with a combined particle velocity-pressure sensor The Journal of the Acoustical Society of America 119, 2826 (2006); 10.1121/1.2188821 Contributed Review: Source-localization algorithms and applications using time of arrival and time difference of arrival measurements Review of Scientific Instruments 87, 041502 (2016); 10.1063/1.4947001 Killer whale (Orcinus orca) behavioral audiograms The Journal of the Acoustical Society of America 141, 2387 (2017); 10.1121/1.4979116 Accuracy of an acoustic location system for monitoring the position of duetting songbirds in tropical forest ͒ Daniel J. Mennilla Department of Biological Sciences, University of Windsor, 401 Sunset Avenue, Windsor, Ontario, Canada N9B3P4 ͒ John M. Burtb Psychology Department, University of Washington, Seattle, Washington 98195 ͒ Kurt M. Fristrupc Natural Sounds Program Center, National Park Service, 1201 Oakridge Drive, Suite 100, Fort Collins, Colorado 80525 ͒ Sandra L. Vehrencampd Lab of Ornithology, Cornell University, 159 Sapsucker Woods Road, Ithaca, New York 14850 ͑Received 1 September 2005; revised 14 February 2006; accepted 14 February 2006͒ A field test was conducted on the accuracy of an eight-microphone acoustic location system designed to triangulate the position of duetting rufous-and-white wrens ͑Thryothorus rufalbus͒ in Costa Rica’s humid evergreen forest. Eight microphones were set up in the breeding territories of 20 pairs of wrens, with an average intermicrophone distance of 75.2±2.6 m. The array of microphones was used to record antiphonal duets broadcast through stereo loudspeakers. The positions of the loudspeakers were then estimated by evaluating the delay with which the eight microphones recorded the broadcast sounds. Position estimates were compared to coordinates surveyed with a global-positioning system ͑GPS͒. The acoustic location system estimated the position of loudspeakers with an error of 2.82±0.26 m and calculated the distance between the “male” and “female” loudspeakers with an error of 2.12±0.42 m. Given the large range of distances between duetting birds, this relatively low level of error demonstrates that the acoustic location system is a useful tool for studying avian duets. Location error was influenced partly by the difficulties inherent in collecting high accuracy GPS coordinates of microphone positions underneath a lush tropical canopy and partly by the complicating influence of irregular topography and thick vegetation on sound transmission. © 2006 Acoustical Society of America. ͓DOI: 10.1121/1.2184988͔ PACS number͑s͒: 43.60.Fg, 43.60.Rw, 43.60.Bf ͓JAS͔ Pages: 2832–2839 I. INTRODUCTION acoustic location systems is uncommon ͑but see Spiesberger, 1999; Hayes et al., 2000; Mohl et al., 2001; Wahlberg et al., An acoustic location system consists of an array of mi- 2001, 2003; Bower and Clark, 2005; Burt and Vehrencamp, crophones that facilitates spatial monitoring of animals based 2005͒. Here we test the accuracy of a passive acoustic loca- on the sounds they produce. Acoustic location systems offer tion system for monitoring the position of duetting songbirds special research advantages because animals’ natural move- in neotropical forest. ment patterns are not inhibited by the passive monitoring Duets occur when two animals, usually breeding part- process and animals can be located even in environments ners, coordinate their songs in overlapping or exactly alter- characterized by visual obstructions ͑McGregor et al., 1997͒. nating bouts of vocalizations. Duets are produced in many Furthermore, the signals exchanged between animals are re- texa, including insects ͑Bailey, 2003͒, frogs ͑Emerson and corded as part of the acoustic location process, facilitating ͒ ͑ ͒ detailed studies of communication processes between mul- Boyd, 1999 , mammals e.g., Geissmann, 2002 , and birds ͑ ͒ tiple individuals simultaneously ͑McGregor et al., 1997; Burt Hall, 2004 . Duetting occurs in more than 220 species of and Vehrencamp, 2005͒. Acoustic location systems have birds and ranks among the most highly coordinated behav- been used extensively to monitor the behavior of many ma- iors known in the animal kingdom ͑Thorpe, 1963; Hall, rine organisms, with particular focus on large mammals ͑e.g., 2004͒. However, much controversy and little consensus sur- Stafford et al., 1998; Mellinger and Clark, 2003; Clark and rounds the ecological and evolutionary significance of duet- Clapham, 2004͒. In contrast, research employing terrestrial ting, as well as the mechanics of vocal coordination by du- etting partners. This is, in part, because many duetting birds live in densely vegetated tropical forest where traditional ͒ a Electronic mail: [email protected] ͒ tools for following and observing animals, such as visual b Electronic mail: [email protected] ͒ c Electronic mail: kurtគ[email protected] tracking or radiotelemetry, are difficult. Nevertheless, spatial ͒ d Electronic mail: [email protected] analyses of duetting may allow for an advanced understand- 2832 J. Acoust. Soc. Am. 119 ͑5͒, May 20060001-4966/2006/119͑5͒/2832/8/$22.50 © 2006 Acoustical Society of America ing of the significance of this intriguing behavior. We were interested in studying duetting behavior in neotropical rufous-and-white wrens ͑Thryothorus rufalbus͒ from a spa- tial perspective. To that end, we developed an eight- microphone acoustic location system for spatial monitoring of the duetting behavior of birds in the humid forests of northwest Costa Rica. In this study we present a test of this system by quantifying the accuracy with which microphone array recordings allowed us to triangulate the position of loudspeakers broadcasting simulated rufous-and-white wren duets. II. METHODS A. Study species and study site Rufous-and-white wrens live in forested and semi- forested habitat throughout much of Central America and northwestern South America. Males and females coordinate their songs to produce both antiphonal and polyphonal duets. The voices of the two sexes are similar, although male songs have significantly lower frequency characteristics and are significantly longer than female songs ͑Mennill and Vehren- camp, 2005͒. Rufous-and-white wrens are largely ground- dwelling songbirds ͑Ahumada, 2001͒ and typically remain in very low vegetation, occasionally ascending to higher perches to sing. At Santa Rosa National Park in northwest Costa Rica ͑10°40ЈN,85°30ЈW͒, our study population of rufous-and- white wrens inhabits the fragments of evergreen moist forest FIG. 1. Photograph of one of the eight microphones used to record playback that remain within the mosaic of regenerating forests that of rufous-and-white wren duets. Microphones were placed on 3.0-m wooden constitute the Guanacaste Conservation Area. The study site poles and attached to trees within wren territories. The average between- microphone distance within each of the 20 array configurations was is characterized by thick vegetation, including a rich vertical 75.2±2.6 m. structure and a lush canopy dominated by guapinol ͑Hyme- nea courbaril͒, milk ͑Brosiumu utile͒, and chicle ͑Manilkara chicle͒ trees. The study site also has diverse topography—the each rufous-and-white wren territory, mounting microphones wrens’ territories follow the sloped stream-sides and small opportunistically where vegetation allowed. Within each ar- escarpments that are associated with the park’s evergreen ray,
Load more

Recommended publications
  • D O C U M E N T E D B R I E F I
    DOCUMENTED BRIEFING R Rapid Force Projection Technologies Assessing the Performance of Advanced Ground Sensors John Matsumura, Randall Steeb, Randall G. Bowdish, Scot Eisenhard, Gail Halverson, Thomas Herbert, Mark Lees, John D. Pinder Prepared for the United States Army Office of the Secretary of Defense Arroyo Center National Defense Research Institute Approved for public release; distribution unlimited PREFACE This documented briefing summarizes the research emerging from an ongoing RAND project that has been supporting the Rapid Force Protection Initiative (RFPI) Advanced Concept Technology Demonstration (ACTD). This project was jointly sponsored by the Office of the Assistant Secretary of the Army for Research, Development, and Acquisition and the Office of the Under Secretary of Defense (Acquisition and Technology) with the goal of exploring new technology concepts for the ACTD. The focus of this year’s research was on advanced ground sensors—specifically the air-deliverable acoustic sensor (ADAS)—with emphasis on how such sensors might fit into the current RFPI hunter–standoff killer concept. High-resolution simulation was used to examine and quantify many of the key aspects of performance, environmental effects, and military utility. This work has been shared with those involved in the ACTD, including the RFPI ACTD program offices. This work should be of interest to defense policymakers, acquisition executives, concept developers, and technologists. The research was conducted in the Force Development and Technology Program of RAND’s Arroyo Center and the Acquisition Technology Policy Center of RAND’s National Defense Research Institute (NDRI). Both the Arroyo Center and NDRI are federally funded research and development centers, the first sponsored by the United States Army and the second sponsored by the Office of the Secretary of Defense, the Joint Staff, the unified commands, and the defense agencies.
    [Show full text]
  • Prestudy on Sonar Transponder
    Prestudy on Sonar Transponder Dag Lindahl & Leigh Boyd, Avalon Innovation September 2018, Västerås, Sweden External consultant: Avalon Innovation AB Dag Lindahl, Business Manager Project North, +4670 454 37 08, [email protected] Leigh Boyd, System Development Engineer +4670 454 43 44, [email protected] Avalon Innovation AB, Skivfilargränd 2 721 30 Västerås, Sweden Org nr: 556546-4525, www.avaloninnovation.com Contractor Marine Center, Municipality of Simrishamn Coordination and editing Vesa Tschernij, Marine Center MARELITT Baltic Lead Partner Municipality of Simrishamn Marine Center, 272 80 Simrishamn, Sweden Contact Vesa Tschernij, Project Leader [email protected] +4673-433 82 87 www.marelittbaltic.eu The project is co-financed by the Interreg Baltic Sea Region Programme 2014-2020. The information and views set out in this report are those of the authors only and do not reflect the official opinion of the INTERREG BSR Programme, nor do they commit the Programme in any way. Cover photo: P-Dyk Table of Contents Introduction 1 Background 3 Sonars and fish finders 3 Active - Beacons 4 Active - Transponders 5 Passive - Reflectors 5 Transmitter power and frequencies 6 Chirp vs. Ping 7 Beam characteristics 7 Propagation in water 7 Returned signal from underwater targets 8 Receiver sensitivity 9 Link- and power budget calculations 9 Transmitter output power 9 Transmitter output efficiency 10 Transmitter lobe directivity and spreading losses. 10 Propagation loss through water to target (and back) 10 Noise 10 Ideas 11 Resonators as energy storage elements or harvesters 11 Conclusions 12 Recommendations for further work 13 Ghost Net Hotline 13 Transponders - to help retrieve nets lost in the future 13 Improving the Sonar Data at the source 14 Computerized Post Processing 14 Map/Database 15 Dispatching algorithm 15 Remotely Operated Vehicles 16 References 17 Introduction Avalon Innovation has been asked to investigate the potential for making a sonar responder, driven by the energy in the sonar pulse.
    [Show full text]
  • WALRUS: Wireless Acoustic Location with Room-Level Resolution Using Ultrasound
    WALRUS: Wireless Acoustic Location with Room-Level Resolution using Ultrasound Gaetano Borriello1,2, Alan Liu1, Tony Offer1, Christopher Palistrant1, Richard Sharp3 1Department of Computer Science & Engineering, University of Washington, Seattle, WA [USA] 2Intel Research Seattle, Seattle, WA [USA] 3Intel Research Cambridge, Cambridge [UK] {[email protected]} Abstract browser can be set up to automatically render web pages associated with the user’s current location. In this paper, we propose a system that uses the The Global Positioning System (GPS) is by far the most wireless networking and microphone interfaces of prevalent example of a location system. It uses signals mobile devices to determine location to room-level from synchronized orbiting satellites to calculate a accuracy. The wireless network provides a three-dimensional position relative to Earth’s synchronizing pulse along with information about the coordinate system. There are two issues with GPS that room. This is accompanied by an ultrasound beacon limit its utility in ubiquitous and mobile computing that allows us to resolve locations to the confines of a scenarios. First, it requires line-of-sight to at least three physical room (since audio is mostly bounded by walls). satellites for 2-D location resolution (four for 3-D). We generate the wireless data and ultrasound pulses Unfortunately, it is difficult to obtain line-of-sight in from the existing PCs in each room; a PDA carried by most environments where users spend most of their a user listens for both signals. Thus, our approach does time (i.e., indoors) and in places where most users live not require special hardware.
    [Show full text]
  • Report of a Workshop to Identify and Assess Technologies to Reduce Ship Strikes of Large Whales
    Report of a Workshop to Identify and Assess Technologies to Reduce Ship Strikes of Large Whales Providence, Rhode Island 8-10 July 2008 Gregory K. Silber, Shannon Bettridge, and David Cottingham U.S. Department of Commerce National Oceanic and Atmospheric Administration National Marine Fisheries Service NOAA Technical Memorandum NMFS-OPR-42 May 2009 Report of a Workshop to Identify and Assess Technologies to Reduce Ship Strikes of Large Whales Providence, Rhode Island 8-10 July 2008 Gregory K. Silber, Shannon Bettridge, and David Cottingham Office of Protected Resources National Marine Fisheries Service 1315 East-West Highway Silver Spring, MD 20910 NOAA Technical Memorandum NMFS-OPR-42 May 2009 U.S. Department of Commerce Gary Locke, Secretary National Oceanic and Atmospheric Administration Jane Lubchenco, Ph.D., Administrator National Marine Fisheries Service James W. Balsiger, Ph.D., Acting Assistant Administrator for Fisheries Suggested citation: Silber, G.K., S. Bettridge, and D. Cottingham. 2009. Report of a workshop to identify and assess technologies to reduce ship strikes of large whales, 8-10 July, 2008, Providence, Rhode Island. U.S. Dep. Commer., NOAA Tech. Memo. NMFS-OPR-42. 55 p. A copy of this report may be obtained from: Office of Protected Resources NOAA, NMFS, F/PR2 1315 East-West Highway Silver Spring, MD 20910 Or online at: http://www.nmfs.noaa.gov/pr ii Acknowledgements We are grateful to the workshop participants for their time and contributions. We appreciate the efforts of the steering committee, which developed the agenda, objectives, and breakout group tasks, selected participants, and assembled background documents. We benefited by the preparation of workshop presentations and background papers by Shannon Bettridge, Robert Becker, Olaf Boebel, Jeff Condiotty, Peter Corkeron, Gary Donoher, Charles Forsyth, Robert Gisiner, Leila Hatch, Richard Merrick, Andrew Pershing, Gregory Silber, Sofie-Marie Van Parijs, and Cheryl M.
    [Show full text]
  • Analysis of Accuracy and Formulation of Criterion for Comparing Two
    ering & ine M g a n n E a Mehdiyev et al. l g , Ind Eng Manage 2014, 3:5 a i e r m t s e DOI: 10.4172/2169-0316.1000145 u n d t n I Industrial Engineering & Management ISSN: 2169-0316 Review Article Open Access Analysis of Accuracy and Formulation of Criterion for Comparing Two Variants of Trilateration Method of Acoustic Location Arif Sh Mehdiyev1, Novruz A Abdullayev2 and Hikmat H Asadov3* 1National Academy of Aviation, Baku, Azerbaijan 2Research Institute of Ministry of Defence Industry, Baku, Azerbaijan 3Research Institute of Aerospace Informatics, Baku, Azerbaijan Abstract In the article the question on development the criterion for comparison of two variants of realization of trilateration method of acoustic location has been considered. It is shown, that upon fulfillment of some condition and sufficiently low level of noises in the signal the choice of the signal strength measuring techniques of trilateration method of location can be preferable. Keywords: Acoustic location; Accuracy; Criterion; Technological and control station that uses a trilateration algorithm to compute explosions; Extinction; Sound speed; Model; Trilateration; Sound a target score for the event. Buoy real-time scoring is provided an strength measurements accuracy of 7 meters while post-processed scores are accurate to 3 meters. Two weapon tests were conducted in 2004 using the GPS Introduction acoustic buoy system. In both cases the impact scores determined According to Krumm [1] location technology is a combination of from the system were within I standard deviation of GPS-derived truth impact scores. methods and techniques for determining a physical location of an object in the real world.
    [Show full text]
  • Tracking Cryptic Animals Using Acoustic Multilateration: a System for Long-Range Wolf Detection Arik Kershenbaum, Jessica L
    Tracking cryptic animals using acoustic multilateration: A system for long-range wolf detection Arik Kershenbaum, Jessica L. Owens, and Sara Waller Citation: The Journal of the Acoustical Society of America 145, 1619 (2019); doi: 10.1121/1.5092973 View online: https://doi.org/10.1121/1.5092973 View Table of Contents: https://asa.scitation.org/toc/jas/145/3 Published by the Acoustical Society of America ARTICLES YOU MAY BE INTERESTED IN The pioneering contributions of Per Stockfleth Enger to fish bioacoustics The Journal of the Acoustical Society of America 145, 1596 (2019); https://doi.org/10.1121/1.5095405 Inverse identification of a higher order viscous parameter of rigid porous media in the high frequency domain The Journal of the Acoustical Society of America 145, 1629 (2019); https://doi.org/10.1121/1.5095403 Artificial speech bandwidth extension improves telephone speech intelligibility and quality in cochlear implant users The Journal of the Acoustical Society of America 145, 1640 (2019); https://doi.org/10.1121/1.5094347 Characterizing horizontally-polarized shear and infragravity vibrational modes in the Arctic sea ice cover using correlation methods The Journal of the Acoustical Society of America 145, 1600 (2019); https://doi.org/10.1121/1.5094343 Swept-frequency ultrasonic phase evaluation of adhesive bonding in tri-layer structures The Journal of the Acoustical Society of America 145, 1609 (2019); https://doi.org/10.1121/1.5094764 Investigation of ultrasonic backscatter using three-dimensional finite element simulations The Journal of the Acoustical Society of America 145, 1584 (2019); https://doi.org/10.1121/1.5094783 Tracking cryptic animals using acoustic multilateration: A system for long-range wolf detection Arik Kershenbauma) Department of Zoology, University of Cambridge, United Kingdom Jessica L.
    [Show full text]
  • 00 Acoustical Ranging Techniques in Embedded Wireless Sensor Networked Devices
    00 Acoustical Ranging Techniques in Embedded Wireless Sensor Networked Devices PRASANT MISRA, University of New South Wales and Swedish Institute of Computer Science NAVINDA KOTTEGE, Commonwealth Scientific and Industrial Research Organization BRANISLAV KUSY, Commonwealth Scientific and Industrial Research Organization DIETHELM OSTRY, Commonwealth Scientific and Industrial Research Organization SANJAY JHA, University of New South Wales Location sensing provides endless opportunities for a wide range of applications in GPS-obstructed environ- ments; where, typically, there is a need for higher degree of accuracy. In this article, we focus on robust range estimation, an important prerequisite for fine-grained localization. Motivated by the promise of acoustic in delivering high ranging accuracy, we present the design, implementation and evaluation of acoustic (both ultrasound and audible) ranging systems. We distill the limitations of acoustic ranging; and present efficient signal designs and detection algorithms to overcome the challenges of coverage, range, accuracy/resolution, tolerance to Doppler’s effect, and audible intensity. We evaluate our proposed techniques experimentally on TWEET, a low-power platform purpose-built for acoustic ranging applications. Our experiments demonstrate an operational range of 20 m (outdoor) and an average accuracy ≈ 2 cm in the ultrasound domain. Finally, we present the design of an audible-range acoustic tracking service that encompasses the benefits of a near- inaudible acoustic broadband chirp and approximately
    [Show full text]
  • Sound Localization in Birds - Physical and Neurophysiological Mechanisms of Sound Localization in the Chicken
    Technische Universität München Lehrstuhl für Zoologie Sound Localization in Birds - Physical and Neurophysiological Mechanisms of Sound Localization in the Chicken Hans A. Schnyder Vollständiger Abdruck der von der Fakultät Wissenschaftszentrum Weihenstephan für Ernährung, Landnutzung und Umwelt der Technischen Universität München zur Erlangung des akademischen Grades eines Doktors der Naturwissenschaften genehmigten Dissertation. Vorsitzender: Prof. Dr. Rudolf Fries Prüfer der Dissertation: 1. Prof. Dr. Harald Luksch 2. Prof. Dr. Bernhard Seeber Die Dissertation wurde am 09.08.2017 bei der Technischen Universität München eingereicht und durch die Fakultät Wissenschaftszentrum Weihenstephan für Ernährung, Landnutzung und Umwelt am 22.01.2018 angenommen. Summary Accurate sound source localization in three-dimensional space is essential for an animal’s orientation and survival. While the horizontal position can be determined by interaural time and intensity differences, localization in elevation was thought to require external structures that modify sound before it reaches the tympanum. Here I show that in birds even without external structures such as pinnae or feather ruffs, the simple shape of their head induces sound modifications that depend on the elevation of the source. A model of localization errors shows that these cues are sufficient to locate sounds in the vertical plane. These results suggest that the head of all birds induces acoustic cues for sound localization in the vertical plane, even in the absence of external ears. Based on these findings, I investigated the neuronal processing of spatial acoustic cues in the midbrain of birds. The avian midbrain is a computational hub for the integration of auditory and visual information. While at early stages of the auditory pathway time and intensity information is processed separately, information from both streams converges at the inferior colliculus (IC).
    [Show full text]
  • The Effect of Sonar on Human Hearing
    11 The Effect of Sonar on Human Hearing Renzo Mora, Sara Penco and Luca Guastini ENT Department, University of Genoa Italy 1. Introduction Human use of the Earth’s oceans has steadily increased over the last century resulting in an increase in anthropogenically produced noise. This noise stems from a variety of sources including commercial shipping, oil drilling and exploration, scientific research and naval sonar. Sonar (for sound navigation and ranging) is a technique that uses sound propagation (usually underwater) to navigate, communicate or to localize: sonar may be used as a means of acoustic location (acoustic location in air was used before the introduction of radar). The term sonar is also used for the equipment used to generate and receive the sound. The range of frequencies used in sonar systems vary from infrasonic to ultrasonic. Sonar uses frequencies which are too much high-pitched (up to 120,000 cycles per second) for human ears to hear. Although there is a growing concern among the public that human generated sounds in the marine environment could have deleterious impacts on aquatic organisms, only few studies address this concern on the effects of these sounds on the human auditory system. The effects of sound on the human auditory system have been the subject of several studies, but one question needs to be resolved yet: the effects caused by the naval sonar. For these reasons this chapter wants to show the effects of active middle frequency sonar on human. Published data from humans under water in literature are scarce and sometimes use different terminology with regard to sound levels.
    [Show full text]
  • Isogeometric Multilevel Quadrature for Forward and Inverse Random Acoustic Scattering
    ISOGEOMETRIC MULTILEVEL QUADRATURE FOR FORWARD AND INVERSE RANDOM ACOUSTIC SCATTERING JURGEN¨ DOLZ,¨ HELMUT HARBRECHT, CARLOS JEREZ-HANCKES, AND MICHAEL MULTERER Abstract. We study the numerical solution of forward and inverse acoustic scat- tering problems by randomly shaped obstacles in three-dimensional space using a fast isogeometric boundary element method. Within the isogeometric framework, realizations of the random scatterer can efficiently be computed by simply up- dating the NURBS mappings which represent the scatterer. This way, we end up with a random deformation field. In particular, we show that the knowledge of the deformation field’s expectation and covariance at the surface of the scatterer are already sufficient to compute the surface Karhunen-Lo`eve expansion. Leveraging on the isogeometric framework, we utilize multilevel quadrature methods for the efficient approximation of quantities of interest, such as the scattered wave's ex- pectation and variance. Computing the wave's Cauchy data at an artificial, fixed interface enclosing the random obstacle, we can also directly infer quantities of interest in free space. Adopting the Bayesian paradigm, we finally compute the expected shape and the variance of the scatterer from noisy measurements of the scattered wave at the artificial interface. Numerical results for the forward and inverse problem are given to demonstrate the feasibility of the proposed approach. 1. Introduction The reliable computer simulation of phenomena where acoustic waves are scattered by obstacles is of great importance in many applications. These include for example arXiv:2010.14613v1 [math.NA] 27 Oct 2020 the modelling of sonar and other methods of acoustic location, as well as outdoor noise propagation and control, especially stemming from automobiles, railways or aircrafts.
    [Show full text]
  • Acoustic Location of Prey by Barn Owls {Tyto Alba) by Roger S
    J. Exp. Biol. (1971), 54. S3S-573 535 With 5 plates and 5 text-figures Printed in Great Britain ACOUSTIC LOCATION OF PREY BY BARN OWLS {TYTO ALBA) BY ROGER S. PAYNE Rockefeller University and New York Zoological Society (Received 20 January 1970) INTRODUCTION The external ears of many species of owls are asymmetrical (Ridgeway, 1914; Stell- bogen, 1930). Although the asymmetry may involve the modification of different structures in different species (Stellbogen, 1930) the result is usually the same: one ear has its opening above the horizontal plane, the other below it. Though Pumphrey (1948), Southern (1955) and others have suggested that the asymmetrical ears of owls may be useful in hunting, prey location by hearing was first demonstrated by Payne & Drury (1958). Work prior to that time had suggested that, in the wild, light levels must often fall below that at which owls can see their prey, thus forcing them to rely upon some non-visual sense in hunting. Dice (1945) calculated the minimum intensi- ties of light required by the barn owl (Tyto alba), the long-eared owl (Asio otus), the barred owl (Strix varia), and the burrowing owl (Speotyto cunicularia) to see a dead mouse from a distance of 6 ft. His rough calculations of the reduction of light due to the absence of the moon, the shade of trees and shrubs, and various degrees of cloud cover led him to conclude that '.. .in the natural habitat of owls the intensity of illumination must often fall below the minimum at which the birds can see their prey'.
    [Show full text]
  • The Effect of Boat Noise and Depth of Water on the Frequency of Echolocation of Bottlenose Dolphins, (Tursiops Truncatus) in Cardigan Bay
    The Effect of Boat Noise and Depth of Water on the Frequency of Echolocation of bottlenose dolphins, (Tursiops truncatus) in Cardigan Bay Elizabeth Shaw Submitted in part candidature for the degree of B.Sc. Zoology, Institute of Biological, Environmental and Rural Sciences, Aberystwyth University MODULE BS32930 – PROJECT I certify that except where indicated, all material in this thesis is the result of my own investigation and references used in preparation of the text have been cited. The work has not previously been submitted as part of any other assessed module, or submitted for any other degree or diploma. NAME (Capitals) ………………………………………………..……….. Signed …………………………………………………………………….. Date ……………………………………………………………………….. 1 Acknowledgements I would like to thank everyone at the Cardigan Bay Marine Wildlife Centre in New Quay. In particular, thank you to Steve Hartley for the use of the boat and acoustical equipment. Thank you also to Sarah Perry, Laura Mears and Rob Smith for their support at the Centre. Finally, thank you to James Harper for guidance with the computer software and acoustical analysis and Rupert Marshall for all his expertise. 2 ABSTRACT As visibility in the marine environment can be poor, cetaceans communicate, navigate and forage acoustically. Anthropogenic noise can propagate over long distances underwater in the marine environment and there is increasing evidence and concern that noise generated by boats in particular, may lead to signal masking in cetaceans. Here I investigate the effect of boat noise on the frequency of echolocation in bottlenose dolphins in Cardigan Bay. This study shows that the bottlenose dolphins (Tursiops truncatus) of Cardigan Bay show plasticity in the frequency of echolocation and are able to reduce this masking effect by altering the frequency of echolocation (Hz) when boats are present.
    [Show full text]