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Acoustic quieting is the process of making machinery quieter by damping vibrations to prevent them from reaching an observer. Machinery vibrates, causing sound waves in air, hydroacoustic waves in water, and mechanical stresses in solid matter.
Noise generated on board ships and submarines can have far-reaching effects on the ability of the vessel to operate safely and efficiently. Military vessels in particular need to be quiet to avoid detection by sonar , so many methods have been used to limit a vessel's noise signature.
The longships were characterized as graceful, long, narrow, and light, with a shallow-draft hull designed for speed.The ship's shallow draft allowed navigation in waters only one meter deep and permitted arbitrary beach landings, while its light weight enabled it to be carried over portages or used bottom-up for shelter in camps.
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.
Carvings of galleys on tombstones from 1350 onward show the construction of these ships. From the 14th century they abandoned a steering-oar in favour of a stern rudder, with a straight stern to suit. From a document of 1624, a galley proper would have 18 to 24 oars, a birlinn 12 to 18 oars and a lymphad fewer still.
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.
Longships were naval vessels made and used by the Vikings from Scandinavia and Iceland for trade, commerce, exploration, and warfare during the Viking Age. The longship's design evolved over many years, as seen in the Nydam and Kvalsund ships. The character and appearance of these ships have been reflected in Scandinavian boatbuilding ...
Industrial noise control is a subset of interior architectural control of noise, with emphasis on specific methods of sound isolation from industrial machinery and for protection of workers at their task stations. Sound masking is the active addition of noise to reduce the annoyance of certain sounds, the opposite of soundproofing.