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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 ...
Two people wearing behind-the-neck earmuffs. Thermal earmuffs are worn for protection from the cold. Because the ears extend from the sides of the head to gather sound waves, they have a high skin surface-area-to-volume ratio, and very little muscle tissue, causing them to be one of the first body parts to become uncomfortably cold as temperatures drop.
Otorhinolaryngology, audiology. Noise-induced hearing loss ( NIHL) is a hearing impairment resulting from exposure to loud sound. People may have a loss of perception of a narrow range of frequencies or impaired perception of sound including sensitivity to sound or ringing in the ears. [ 1] When exposure to hazards such as noise occur at work ...
Ballistic eyewear. Ballistic eyewear is a form of glasses or goggles that protect from small projectiles and fragments. For the U.S. military, choices are listed on the Authorized Protective Eyewear List (APEL). [ 1] Ballistic eyewear including examples that meet APEL requirements are commercially available for anyone who wishes to buy it.
Noise -cancelling headphones alongside a carry case. Noise-cancelling headphones are headphones which suppress unwanted ambient sounds using active noise control. This is distinct from passive headphones which, if they reduce ambient sounds at all, use techniques such as soundproofing . Noise cancellation makes it possible to listen to audio ...
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 ...
In contrast to most other eye glasses, shooting glasses usually only have one lens that corrects the ametropia of the dominant eye, which is used for aiming.This lens is selected in such a way that the maximum visual acuity lies on the font sight line element near the muzzle of the (non-magnifying) open type or diopter and globe type match sight line elements to get three points positioned in ...