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Humbpback whales use sound to communicate adn navigate (Photo © Vojtech Soukup Agency: Dreamstime) |
Whales rely on sound more than sight underwater. The ocean depths can be dark and murky, making it difficult to see objects clearly. Whales use sound to navigate, to find food, and to communicate. Sound travels much farther underwater than in the air. Toothed whales, like the killer whale, use echolation to hunt for food. They send out sound waves that bounce off objects and echo back. The whales can determine the distance, density, and even size of an object based on the speed and intensity of the echoes that bounce back. In recent years, scientists have learned that baleen whales use low-frequency sound for navigation. They help to locate themselves in the vast ocean by using sound waves to identify familiar landmarks. Migrating whales can determine the proximity of the coastline from the sound of waves crashing. Detecting the sounds of oncoming boats is also important.
The whales’ ability to rely on sound has been affected by increased noise pollution in the ocean. Manmade noise can interfere with whales’ communication and navigation. Underwater noise pollution comes from a variety of sources: large ships and other vessels, underwater construction and mining, explosives, and military operations. Noise can be stressful, and even harmful, to whales. Low frequency sonar systems, used by the navy to detect submarines, use a similar frequency as the whales and can interfere with their ability to communicate. Recent studies have shown that high levels of these sound waves may physically injure and disorient whales exposed to them.
Humans rely more on vision than sound. We know, though, that loud noises can be distracting and even painful. Toxic noise for people can include hair dryers, leaf blowers, loud music on headsets or earphones. We can only imagine the effect that noise pollution has on the whales.
One human auditory perceptual skill that is somewhat similar to the whales’ use of sound is auditory figure-ground. It’s the ability to distinguish a specific sound from other sounds or background noise. Students must learn to do it when they are in the classroom and listening to the teacher. They have to separate the teacher’s voice from other sounds inside and outside the room. Try some of the following auditory perception activities. You can also go to the following web links to listen to recordings of whales sounds.
NOAA, the National Oceanic and Atmospheric Administration, has a site with audio files of whale sounds. Go to www.noaa.gov/whales/
References:
www.oceanmammalinst.org
www.dosits.org/animals/intro.htm
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