- How they hear sounds
- How they use sound when they are feeding
- How they use sound to communicate
- How they use sound to navigate
- What are the effects of anthropogenic (human produced) sound on marine mammals
- How can one measure the reaction of marine mammals to sound
There are also more advanced discussions of scientific methods.
Sound and hearing are very important to marine mammals and a recent study has shown that right whales compared to the 1970s are shouting (frequency shift) because of the increased level of noise in their environment from human sources. The paper was in the Journal of the Acoustical Society of America, Volume 122, Issue 6, pp. 3725-3731 and is entitled "Short- and long-term changes in right whale calling behavior".
Reducing the amount of anthropogenic noise in the marine environment is a bit of a Catch 22. Given that fast moving vessels are problems for right whales, completely silent fast vessels may pose a greater risk than one making low noise. Moreover, most noise from a vessel comes from the propellers and the bow is a relatively quiet zone which may confuse right whales and other marine mammals into thinking they are safe at the bow of large vessels. Using sound deterrents on the bow are unproven. Experiments playing sounds to right whales produced inconsistent results and when the whales did respond to a particular sound, the whale stopped what it was doing and came to just below the surface to listen to the sound. This, of course, would bring the whale into a greater danger zone than if the whale had not responded to the sound. Scaring whales away from vessels is a complicated problem. It is, however, very important to reduce any masking effects of marine mammals communications so they are able to hear each other over broad expanses of ocean.
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