Search results
Results from the WOW.Com Content Network
Output of a computer model of underwater acoustic propagation in a simplified ocean environment. A seafloor map produced by multibeam sonar. Underwater acoustics (also known as hydroacoustics) is the study of the propagation of sound in water and the interaction of the mechanical waves that constitute sound with the water, its contents and its boundaries.
Biomass estimation is a method of detecting and quantifying fish and other marine organisms using sonar technology. [1] An acoustic transducer emits a brief, focused pulse of sound into the water. If the sound encounters objects that are of different density than the surrounding medium, such as fish, they reflect some sound back toward the source.
While terrestrial animals often have a uniform method of producing and detecting sounds, aquatic animals have a range of mechanisms to produce and detect both vocal and non-vocal sounds. [7] In terms of sound production, fish can produce sounds such as boat-whistles, grunts and croaks using their swim bladder or pectoral fin.
Sonar (sound navigation and ranging or sonic navigation and ranging) [2] is a technique that uses sound propagation (usually underwater, as in submarine navigation) to navigate, measure distances , communicate with or detect objects on or under the surface of the water, such as other vessels.
Bloop was an ultra-low-frequency, high amplitude underwater sound detected by the U.S. National Oceanic and Atmospheric Administration (NOAA) in 1997. [1]
The lateral line in fish and aquatic forms of amphibians is a detection system of water currents, consisting mostly of vortices. The lateral line is also sensitive to low-frequency vibrations. It is used primarily for navigation, hunting, and schooling. The mechanoreceptors are hair cells, the same mechanoreceptors for vestibular sense and hearing.
At high frequency settings, high chart speeds, such fathometers give a picture of the bottom and any intervening large or schooling fish that can be related to position. Fathometers of the constant recording type are still mandated for all large vessels (100+ tons displacement) in restricted waters (i.e. generally, within 15 miles (24 km) of land).
Sound parameters such as frequency and modulation method are chosen for optimal detectability, and signal level. For oceanic environments, frequencies less than 100 kHz range are often used [ citation needed ] , while frequencies of several hundreds of kilohertz are more common in for studies in rivers and lakes [ citation needed ] .