2. The NRR value of anti-noise earplugs is the sound insulation standard formulated by the US Environmental Protection Agency. The greater the NRR value, the better the sound insulation effect.
3, earplug slow rebound characteristics, that is, how long it will take to recover after being flattened by hand, at least 20 seconds.
4, the comfort of earplugs, bad earplugs will feel very swollen after wearing, excellent products have basically no discomfort after wearing. At present, the most common shapes of anti-noise earplugs are 3M brand bullet earplugs, as well as patented rocket earplugs (T-shaped), horn earplugs, cylindrical earplugs and triangular earplugs.
At present, the earplugs and earmuffs with the best anti-noise effect are MAX 1 and SE 1340, with decibels of 37 and 38 respectively. Our normal speaking voice is about 50 decibels, which can reduce the noise by more than 30 decibels. If earplugs and earmuffs are used together, the effect will be better, but at present, there is no anti-noise product with complete sound insulation.
Extended data:
Earplugs, small receivers, can be inserted into the ear, often used in radios and hearing AIDS. It can also be stuffed in the ear to prevent water from entering the ear when swimming, and can also be used to reduce noise interference, that is, anti-noise earplugs, sleep earplugs, etc.
The principle of sleep earplugs is similar to that of anti-noise earplugs. In order to achieve the purpose of comfortable daily sleep, they use soft slow-rebound materials, but the anti-noise performance can basically reach or even exceed the level of silicone earplugs, so the quality is better than the general labor protection earplugs.
Reference link: China earplug network