Ocean Acoustics

To understand the effects of ocean noise, there are a number of themes that need to be addressed. This section of AE.org will feature summaries that will help you to enter the underwater sounding world a bit more informed. Some have been written by AEI founder Jim Cummings, and some come from outside sources.

From AEI:
Natural Sources of Noise in the Sea
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Ambient Noise in the Sea: Common sources of human noise
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Frequency Spectrum of noise and species-specific sensitivity
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Short and Long Duration Sounds/Rise Times
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Measurement Issues: dB in Air and Water
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Is it Valid to Compare dB in Air and Water? Across species?
A handy chart, along with reasons for taking dB thresholds with a sea of salt
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Measurement Issues: Differing Measurement Systems
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Transmission Loss: Variations between Source Level and Received Level of Sound
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From Others:
Marine Mammal Commission Ocean Acoustics Primer
A short booklet published online by the MMC in 2008. [GO THERE]

National Academies of Science Ocean Sounds Tutorial
"Sounding Out the Ocean's Secrets", with sections on navigation by sound, sound propagation, deep sound channel, acoustic monitoring, and geophysics. [GO THERE]

Sons de Mar
Overview of ocean bioacoustics and anthropogenic noise sources, presented in an educational format. A nice graphic "Presentation" allows students to click and hear a variety of whales and human noise sources. From the Applied Bioacoustics Laboratory. [GO THERE]

NOAA Ocean Acoustics Overview and Tutorial
The National Oceanographic and Atmospheric Administration website features a good summary of ocean acoustics information, and a several-page tutorial on specific topics. [GO THERE]

What is a Decibel?
By Joe Wolfe at the University of Southern Wales, a good introduction, with graphs and sound samples. Gives a concrete sense of the audible, physical experience of increasing decibel levels. [GO THERE]

Listening Underwater
Whale acoustics researcher and musician Lisa Walker has a section on her site that goes into some detail on the nature of listening underwater, and how it is different for humans and sea creatures. [GO THERE]

NOVA "Sounding out the Secrets of the Sea"
A straightforward set of pages that explain the use of sound by fish and cetaceans, and provides an overview of human noise sources; includes useful diagrams and several linked threads. [GO THERE]

Discovery of Sound in the Sea
A fantastic set of pages put together by the University of Rhode Island. Includes sections on the importance of sound to marine animals, the effects of human noises, and sound propagation. [GO THERE]