Seven miles deep, ocean still a noisy place

For what may be the first time, NOAA and partner scientists eavesdropped on the deepest part of the world's ocean and instead of finding a sea of silence, discovered a cacophony of sounds both natural and caused by humans.

Undersea volcano gave off signals before eruption in 2011

(Phys.org) -- A team of scientists that last year created waves by correctly forecasting the 2011 eruption of Axial Seamount years in advance now says that the undersea volcano located some 250 miles off the Oregon coast ...

Ecologists record and study deep-sea fish noises

University of Massachusetts Amherst fish biologists have published one of the first studies of deep-sea fish sounds in more than 50 years, collected from the sea floor about 2,237 feet (682 meters) below the North Atlantic. ...

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Hydrophone

A hydrophone (Greek "hydro" = "water" and "phone" = "sound") is a microphone designed to be used underwater for recording or listening to underwater sound. Most hydrophones are based on a piezoelectric transducer that generates electricity when subjected to a pressure change. Such piezoelectric materials, or transducers can convert a sound signal into an electrical signal since sound is a pressure wave. Some transducers can also serve as a projector, but not all have this capability, and may be destroyed if used in such a manner.

A hydrophone can "listen" to sound in air, but will be less sensitive due to its design as having a good acoustic impedance match to water, the denser fluid. Likewise, a microphone can be buried in the ground, or immersed in water if it is put in a waterproof container, but will give similarly poor performance due to the similarly bad acoustic impedance match.

This text uses material from Wikipedia, licensed under CC BY-SA