Acoustic Loggers Research Articles

Keynote Address: Seismic surveys and marine life: why is it so difficult to let the science speak?

The offshore oil and gas exploration industry in Australia (and worldwide) has conducted extensive research and monitoring programs which have provided valuable insights into the nature of seismic signals in different water depths and the behaviour of marine animals such as whales, dolphins and fish in the vicinity of seismic surveys. Despite this, we in Australia still have to operate marine seismic surveys under a set of protocols covering the interaction between seismic surveys and whales that are the most stringent (over-precautionary?) in the world. Why can this be so? If all regulators and all interested parties are looking at the same body of science; i) why are the protocols for interaction between seismic surveys and whales not consistent throughout the world and ii) why is the seismic industry accused of adversely impacting marine life when, after 40 years of marine exploration using airgun arrays, there is no real evidence of this? This presentation briefly describes the results achieved from using such techniques as towed PAM (passive acoustic monitoring), seabed acoustic loggers, shipboard observations (synthesis of MMO data), aerial surveys, etc. It then goes on to explore the main reasons why the industry finds it so difficult to get its message across. These reasons include the lack of awareness of many geophysicists, asset managers and companies about the challenges involved in acquiring seismic data in the first place, the complexity of the science, the difficulties involved in collating it into a meaningful result, the fact that the science is often interpreted or portions of it selected by those who have a biased opinion (as opposed to panels that provide a balanced view) and the reluctance of many companies in the industry to challenge the often emotive and inaccurate accusations by some environmental groups and the media.

Long-term variations of ice breaking noise in Antarctica

Numerous low frequency transient signals arriving from Antarctica have been detected in five-year sea noise recordings in 2002-2006 at the hydroacoustic listening station deployed off Cape Leeuwin in Western Australia as part of the International Monitoring System of the Comprehensive Nuclear-Test-Ban Treaty. The majority of these signals consist of a single arrival of mode 1 which dominates the higher modes and undergoes strong frequency dispersion due to long-range propagation in the polar ocean environment. These signals are believed to be emitted primarily by ice rifting and breaking events on the Antarctic shelf. Several regions along the Antarctic coast associated with certain glaciers and ice tongues were found to persistently be much more active in generating ice noise than other parts of the Antarctic shelf. An analysis of long-term changes in the frequency of occurrence of ice events showed noticeable seasonal cycles, but did not reveal any significant interannual variations against the background of short-term fluctuations. Some of the ice events detected at the Cape Leeuwin station were also identified in sea noise recordings made on autonomous acoustic loggers deployed on the Antarctic shelf, which allowed us to investigate characteristics of the acoustic signals from ice events near their origins.

Locating leaks from water supply pipes using the passive acoustic method

Research Article| December 01 2005 Locating leaks from water supply pipes using the passive acoustic method A. Lockwood; A. Lockwood 1Westlakes Scientific Consulting Ltd, The Princess Royal Building, Westlakes Science and Technology Park, Moor RowCumbria, CA24 3LN, UK, and Faculty of Earth and Environment, University of Leeds, Leeds, LS2 9JT, UK Search for other works by this author on: This Site PubMed Google Scholar T. Murray; T. Murray 2Department of Geography, University of Wales Swansea, Singleton ParkSwansea, SA2 8PP, UK Search for other works by this author on: This Site PubMed Google Scholar G. Stuart; G. Stuart 3Faculty of Earth and Environment, University of Leeds, Leeds, LS2 9JT, UK Search for other works by this author on: This Site PubMed Google Scholar L. Scudder L. Scudder 4Thames Water PLC, Spencer House, Manor Farm Road, Reading, RG2 0JN, UK Search for other works by this author on: This Site PubMed Google Scholar Journal of Water Supply: Research and Technology-Aqua (2005) 54 (8): 519–530. https://doi.org/10.2166/aqua.2005.0046 Article history Received: September 10 2004 Accepted: September 29 2005 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Share Icon Share Twitter LinkedIn Tools Icon Tools Cite Icon Cite Permissions Search Site Search nav search search input Search input auto suggest search filter All ContentAll JournalsThis Journal Search Advanced Search Citation A. Lockwood, T. Murray, G. Stuart, L. Scudder; Locating leaks from water supply pipes using the passive acoustic method. Journal of Water Supply: Research and Technology-Aqua 1 December 2005; 54 (8): 519–530. doi: https://doi.org/10.2166/aqua.2005.0046 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex Acoustic techniques for locating water leaks make use of the noise created by water leaking from a pipe; most require contact with the pipe network. This paper reports on the location of leaks in urban environments using acoustic loggers at the ground surface itself, remote from the pipe. An increase in the root-mean-squared (RMS) acoustic signal amplitude of ∼7.5 to ∼12.5 dB above background was detected above leaks from both plastic and metal pipes. The peak frequency of the acoustic signal was ∼750 Hz above a metal pipe, decreasing to ∼400 Hz at a distance of 1 m. Plastic pipes had a lower source leak frequency (below 700 Hz) and dropped to ∼350 Hz at 1 m. Background noise was predominantly below 150 Hz, which was suppressed using a high pass filter. The RMS signal amplitude directly above the leak decreased with increasing pipe depth, but was detectable for all pipe depths (0.4–1.0 m) covered in this work. An array of acoustic sensors at the surface can successfully detect and locate leaks without direct access to the pipe network, providing a robust and rapid leak location method. shallow acoustic, urban environment, water leak location, water supply This content is only available as a PDF. © IWA Publishing 2005 You do not currently have access to this content.

Directional acoustic logger apparatus and method

An acoustic logging apparatus and method are disclosed for determining the direction of a subsurface noise source, such as a blowout well or fluid channeling behind well casing. The apparatus comprises cylindrical piezoelectric crystal transducers processed to buck each other. The method employs such an apparatus and includes generating and observing output from the crystals. The direction of the noise relative to the position of the apparatus is indicated by determining the position of the crystal transducers when their phase and amplitude differences are at a minimum. The transducer leading in phase at a point perpendicular to said position is the transducer closest to the noise source and is used to indicate the absolute direction of the noise.