Do you know SNR and NRR?We are always exposed to all kinds of noise in our daily life. However, because of the wrong use of the ear, many people have ear diseases. With more and more people deaf, hearing protection has attracted more and more attention. Therefore, the industry of hearing protection has also flourished.
In order to provide consumers with appropriate basis and standards for hearing protection products, the European Union and the United States have launched noise reduction performance standards for anti noise products, mainly including SNR and NRR standards. Among them, SNR is an international standard and NRR is an American Standard.
let’s talk about popular science. What are SNR and NRR?
What are SNR and NRR?
SNR: single value noise reduction value detected according to international standard ISO4969-2. It is a standard to evaluate the anti noise performance of hearing protection products by detecting the attenuation degree of HML three frequency noise.
NNR: in accordance with American Standard ANSI S3 Single value noise reduction value detected by 19-1974 standard. It is a standard for measuring the anti noise performance of hearing protection products issued by the American environmental protection organization (EPA) in 1979.
At present, the NRR of anti noise products sold on the market is roughly in the range of 0-40db.
How to calculate SNR and NRR?
- Calculation method of SNR value
In the code for 《hearing protection of employees in industrial enterprises》, it is clear that the actual noise value accepted by human ears calculated by SNR is:
Actual noise value on site – SNR * 0.6.
- Calculation method of NRR value:
《AQ / T 4276-2016 guidelines for risk management of noise occupational》hazards specifies that the actual noise value accepted by human ears calculated by NRR is:
Actual noise value on site – (NRR-7) / 2.
For example, if we are in an office and the site noise level is 70dB, using the calculation method of SNR value, the actual site noise value after wearing silicone mud earplugs is about 54dB, which is close to the normal conversation sound.
Then silicone mud earplugs can achieve noise reduction effect.
Similarly, if the product package contains NRR standard, its calculation method can also be used to obtain the actual noise value accepted by human ears.
Choose hearing protection products
Generally, the selection of hearing protection articles is calculated according to the noise volume of the environment and the decibel value that can be reduced by the protective articles to see whether the ideal noise exposure value is reached.
At present, sponge earplugs with slow return elasticity are more popular in the world, which are convenient to carry and store, good noise reduction effect and high comfort.
Of course, earmuffs can also be directly selected, and some can be used directly with safety helmets; Some can be shockproof, some can be folded, etc.
The use effect of ear muffs and earplugs is affected by whether they are worn correctly. Only when they are worn correctly can they give full play to their role.