Monday, December 2, 2013

Perception of Sound Under Water 
                Humans hear in two different ways according to NOAA (National Oceanic and Atmospheric Administration, “through air conductivity or vibrations in the audio bones from our inner ear, and through bone conductivity or vibrations in our skull”. When we hear under water we use bone conductivity. This is the reason why it is harder to hear underwater since it is 40 percent less effective than air conductivity. It is also harder to hear underwater because the eardrums cannot vibrate due to water filling the outer portion of the outer ear.
                Since sound travels 4.3 times faster underwater, this causes hearing to be more difficult. This is because sound is almost simultaneously perceived by both ears it makes it difficult to orient oneself to a sound underwater. In air the sound will reach one ear .00003 seconds earlier and we are able to identify the source because of this.Even though we do not notice the time difference consciously, our brains are able to interpret the direction of the sound.
Another problem could occur when a person is in a swimming pool and there are fast-traveling sound waves coming from an underwater speaker. The sound waves bounce off the bottom, surface and sides of the pool. The person will receive the sound from all directions, and the human brain will not be able to process the original sound source.

- Justine Foster

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