Acoustical oceanography is the use of underwater sound to study the sea

Sea

A sea generally refers to a large body of salt water, but the term is used in other contexts as well. Most commonly, it means a large expanse of saline water connected with an ocean, and is commonly used as a synonym for ocean...

, its boundaries and its contents.

History

The earliest and most widespread use of sound and sonar

Sonar

Sonar is a technique that uses sound propagation to navigate, communicate with or detect other vessels...

 technology to study the properties of the sea is the use of an echo sounder to measure water depth. The development of high resolution sonar in the second half of the 20th century made it possible to not just detect underwater objects but to classify them and even image them.

Important contributions to acoustical oceanography have been made by:

• Walter Munk
  Walter Munk
  Walter Heinrich Munk is an American physical oceanographer. He is professor of geophysics emeritus and holds the Secretary of the Navy/Chief of Naval Operations Oceanography Chair at Scripps Institution of Oceanography in La Jolla, California.-Early life:Born in 1917 in Vienna, Austria-Hungary,...
  
  
• Hank Medwin
• John L Spiesberger
• C C Leroy
• David E Weston
• D. Van Holliday
  D. Van Holliday
  Dr. Dale Vance Holliday was born in Ennis, Texas and attended the University of Texas at Austin. He graduated with a B.S. and M.A. in Physics and did extensive theoretical and experimental research on the Mössbauer effect...
  
  
• Charles Greenlaw

Applications

Applications of acoustical oceanography include:

• fish population surveys
• classification of fish species and other biota
• rain rate measurement
• wind speed measurement
• water depth measurement
• seabed classification
• ocean acoustic tomography
  Ocean acoustic tomography
  Ocean Acoustic Tomography is a technique used to measure temperatures and currents over large regions of the ocean. On ocean basin scales, this technique is also known as acoustic thermometry. The technique relies on precisely measuring the time it takes sound signals to travel between two...
  
  
• global thermometry
• monitoring of ocean-atmospheric gas exchange

Marine biology

The study of marine life, from microplankton

Plankton

Plankton are any drifting organisms that inhabit the pelagic zone of oceans, seas, or bodies of fresh water. That is, plankton are defined by their ecological niche rather than phylogenetic or taxonomic classification...

 to the blue whale

Blue Whale

The blue whale is a marine mammal belonging to the suborder of baleen whales . At in length and or more in weight, it is the largest known animal to have ever existed....

, uses bioacoustics

Bioacoustics

Bioacoustics is a cross-disciplinary science that combines biology and acoustics. Usually it refers to the investigation of sound production, dispersion through elastic media, and reception in animals, including humans. This involves neurophysiological and anatomical basis of sound production and...

.