Mid-Frequency Sonar Interactions with Beaked Whales

• Main Authors: Foote, Kenneth G., Feijoo, Gonzalo R.
• Other Authors: WOODS HOLE OCEANOGRAPHIC INSTITUTION MA DEPT OF APPLIED OCEAN PHYSICS AND ENGINEERING
• Format: Text
• Language: English
• Published: 2011
• Subjects: Biology; Acoustic Detection and Detectors; *WHALES; *AQUATIC ANIMALS; *SONAR; *ACOUSTICS; INTERACTIONS; PHYSICAL PROPERTIES; FINITE ELEMENT ANALYSIS; ELASTIC PROPERTIES; SENSITIVITY; EXPLOSIVES; PRESSURE MEASUREMENT; THREE DIMENSIONAL; MATHEMATICAL ANALYSIS; PRESSURE; NAVAL OPERATIONS; MILITARY EXERCISES; ANATOMY; EQUATIONS; ONLINE SYSTEMS; PLANE WAVES; COMPUTERIZED TOMOGRAPHY; MODELS; VALIDATION; TOURMALINE; TISSUES(BIOLOGY); DETECTORS; BEAKED WHALES; Harbour porpoise; Phocoena phocoena
• Online Access: http://www.dtic.mil/docs/citations/ADA545359; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA545359

Naval exercises involving use of military sonars operating in the mid-frequency (MF) band, 1-10 kHz, have been implicated in the strandings of marine mammals, especially beaked whales. Understanding the cause or causes of the greater sensitivity of beaked whales to MF sonar has stimulated much speculation and thought. The suspicion that there is a deep connection to anatomy instigated the project summarized here, namely "Mid-frequency sonar interactions with beaked whales." The ambition of this was to develop a tool that would enable researchers to predict sonar-induced acoustic fields inside beaked whales as well as inside other marine mammals. The tool, called the Virtual Beaked Whale, was to be an interactive online modeling and visualization system. Formidable resources were contributed to development of this system both by ONR and by the Woods Hole Oceanographic Institution, but it was not completed. However, the scope and components of such a system were outlined in detail, and some of these components were also developed. This included specification of a finite-element method (FEM) to solve the full-diffraction wave equation for acoustic interactions with a complicated, heterogeneous body; modeling the three-dimensional anatomy of exemplary marine mammal specimens; and assigning physical properties to the diverse, constituent tissues. Beaked whales are large: a mature Cuviers beaked whale {Ziphius cavirostris) can be 8.5 m in length. This presents two difficulties. Firstly, detailed anatomical data cannot be obtained on a whole specimen by computed tomography (CT) scanning. Thus, a synthetic model of a beaked whale was developed based on CT scans of (i) the head of a freshly dead Cuvier's beaked whale, and (ii) the body of a harbour porpoise {Phocoena phocoena).