Marine Mammal Observers

Contents

• Distributing, monitoring and recording audio signals from sonobuoy radio receivers
• Installation and configuration of streaming audio server
• Marine Mammals Observation
• Seismic sources: Impact on marine life

Distributing, monitoring and recording audio signals from sonobuoy radio receivers

There are three ways to distribute audio signals from the radio receivers.

• Power amplifier and speakers
  A simple amplifier and loadspeaker on the flying bridge provides MMO's with an audible impression of what's going on below the surface. Marine mammals that “emits” low-frequency sounds (10-100Hz) will be hard to detect, however.
  
• Stereo FM radio transmitter
  A low-power (< 1W) stereo FM transmitter using the common FM frequency range of 88 – 108 Mhz can be used to transmit the two audio signals from the sonobuoy receivers. MMO's can use FM-walkmans with earphones in areas of the ship that are covered by the radio signals. We will use the TX1 1W Stereo Transmitter purchased from Broadcast Warehouse.
  
• Streaming “net radio”
  As a trial, audio signals from the sonobouy radio receivers will be distributed from a streaming server over Healy's data network - like a net radio. You can listen in from WinAmp or similar programs, and open analyzis or recording programs.

Three audio analyzing programs are mentioned here; Ishmael and Syrinx for Windows, and Baudline for Linux.

Marine Mammal scientists often use Ishmael, written by Dave Mellinger at NOAA, to analyze and record sounds of interest. Besides operating Ishmael in a continuos monitoring mode, you can also set recording trigger conditions based on both energy content of the signal and correlations with known signals. There is also beam forming feature that can be useful if you have two hydrophones. The crucial point is that the sound channels that Ishmael uses as inputs is determined by the recording mixer settings on your computer - so you can use a microphone connected to the PC sound card, or the streaming audio that is received from a net radio.

Screenshot of Ishmael, monitoring audio received from a net radio station (click to enlarge). Notice the recording mixer setting.

An alternative is Syrinx, written by John Burt, a Windows program for spectral analysis, editing, and playback of acoustic signals, but not directly targeting marine mammals, as Ishmael seems to be. Here's a screenshot:

Screenshot of Syrinx, also monitoring audio received from a net radio station (click to enlarge).

A Linux option is a program called Baudline. A screenshot showing Baudline, it's Input Devices selection window and a streaming net radio window is shown below. Baudline is easy to install: Download tgz file, untar, enter Baudline directory and execute the program by writing ./baudline. Use a Linux mixer program (like KMix) to select proper source, in combination with Baudline's own Input Source select window (righ click main window to access it). To record data with Baudline, right click the main window, then select Output > Play deck.

Screenshot of Baudline (click to enlarge).

Thanks to Jason Gedamke, Univ. of California, Santa Cruz, for providing information on Ishmael and Syrinx.

Installation and configuration of streaming audio server

• Installation and configuration, Windows based streaming server.
• Installation and configuration, Linux based streaming server.

Marine Mammals Observation

• Bering Sea Right Whales: Acoustic Recordings and Public Outreach, by Dr. John A. Hildebrand and Lisa M. Munger, Scripps Institution of Oceanography
• Impacts of Marine Acoustic Technology on the Antarctic Environment, by SCAR Ad Hoc Group on marine acoustic technology and the environment.

Seismic sources: Impact on marine life

The following documents are stored on IFG web server:

• Impact of seismic surveys on marine life, by Ingebret Gausland, Statoil, Norway (pdf, 468 kB)
• Introduction to air guns and air-gun arrays, by William Dragoset, Western Geophysical, Houston, U.S. (pdf, 2.1 MB)
• A brief overview of seismic air-gun arrays, by Jack Caldwell, TomoSeis, Houston, U.S. and William Dragoset, Western Geophysical, Houston, U.S. (pdf, 1.6MB)
• MMS acoustic studies in the Gulf of Mexico, FY 2000, by William Lang, Minerals Management Service, New Orleans, Louisiana, U.S.

Pressure outputs from Sercel (Sodera) airguns, ref.: G. GUN, The Recoilless Air gun, Sercel (Sodera). Page numbers are with reference to this document.

University of Bergen
Dept. of Earth Science (IFG)
Allé gt. 41, N-5007 Bergen, Norway
Tel: (+47) 5558 3600