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Active noise control ( ANC ), also known as noise cancellation ( NC ), or active noise reduction ( ANR ), is a method for reducing unwanted sound by the addition of a second sound specifically designed to cancel the first. The concept was first developed in the late 1930s; later developmental work that began in the 1950s eventually resulted in ...
A hearing protection device, also known as a HPD, is an ear protection device worn in or over the ears while exposed to hazardous noise and provide hearing protection to help prevent noise-induced hearing loss. HPDs reduce the level of the noise entering the ear. HPDs can also protect against other effects of noise exposure such as tinnitus and ...
Silencer (firearms) A silencer, also known as a sound suppressor, suppressor, or sound moderator, is a muzzle device that suppresses the blast created when a gun ( firearm or airgun) is discharged, thereby reducing the acoustic intensity of the muzzle report (sound of a gunshot) and jump, by modulating the speed and pressure of the propellant ...
Using both ear muffs (whether passive or active) and earplugs simultaneously results in maximum protection, but the efficacy of such combined protection relative to preventing permanent ear damage is inconclusive, with evidence indicating that a combined noise reduction ratio (NRR) of only 36 dB (C-weighted) is the maximum possible using ear ...
Fogel is considered to be the inventor of active noise cancellation, and he designed one of the first noise-cancelling headphones systems. Later on, Willard Meeker designed an active noise control model that was applied to circumaural earmuffs for advanced hearing protection. Noise-cancelling aviation headsets are now commonly available. [5] [6]
A gyro gunsight (G.G.S.) is a modification of the non-magnifying reflector sight in which target lead (the amount of aim-off in front of a moving target) and bullet drop are calculated automatically. The first examples were developed in Britain just before the Second World War for use during aerial combat, and more advanced models were common ...
Shooting Detector Diagram. A gunfire locator or gunshot detection system is a system that detects and conveys the location of gunfire or other weapon fire using acoustic, vibration, optical, or potentially other types of sensors, as well as a combination of such sensors. These systems are used by law enforcement, security, military, government ...
The AN/SPY-1[ a] is a United States Navy 3D radar system manufactured by Lockheed Martin. The array is a passive electronically scanned system and a key component of the Aegis Combat System. The system is computer controlled and uses four complementary antennas to provide 360-degree coverage. The system was first installed in 1973 on USS Norton ...