Noise Reduction Rating often abbreviated as NRR is a unit (ranges from 0 to 30) that is used to find the effectiveness of the hearing protection devices (HPD) e.g. earplugs that can reduce the noise and protects human’s ear from loud noises.
The potential of a noise reduction device depends on the NRR, the higher it will be the greater effect it will have. Noise Reduction Rating is also sometimes referred to as a hearing protection rating.
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How NRR Changes Noise Exposure?
When HPD (Hearing Protection Device) is worn the level of noise exposure is totally based on the Noise Reduction Rating of your HPD. But keep in mind the protection device you are using doesn’t reduce the surrounding noise by the exact number of decibels of your HPD’s NRR.
Let me explain this with an example, suppose that you are in a party and the sound exposure at that particular place is 100 dB and you have worn HPD of 29 dB, your level of exposure will not be 71 dB, in fact, it will be 89dB.
How to Calculate Actual Noise Exposure?
To calculate the actual noise exposure you need to follow the below formula.
Formula: NRR of HPD minus 7 divide by 2 subtract the answer from the real noise exposure in the surrounding is equal to the noise exposure at your ears.
Let’s put the values from the above example in our formula for even more clear understandings.
| Real Noise Exposure at Surrounding: | 100 dB (A) |
| NRR of hearing protectors: | 29 dB |
| Subtract 7 dB from NRR: | 29 dB – 7 dB = 22 dB |
| Divide it by 2: | 22 / 2 = 11 dB |
| Subtract 11 dB from real Noise exposure at surrounding: | 100 – 11 = 89 dB |
How Does Dual HPD Effects NRR?
When two hearing protection devices are used at the same time, such as you can use earplugs and earmuffs at the same time then their individual NRRs are not added, instead, we just add 5 dB to the higher hearing protector.
Let me explain this with an example, if you are earplugs of 29 dB and Earmuffs of 27 dB then we will add 5 dB to the higher one HPD which is earplug of 29 dB. So, 29 + 5 = 34 dB. This will be the actual dB after using two HPD at the same time.
Required Standards for Hearing Protectors:
Every hearing protector device has to comply with the strict standards of the ANSI/ASA S12.6-2016 & OSHA.
These standards define the ways of measuring, analyzing, noise reduction capability of hearing protection devices.
At which level of Noise Hearing Protection is required?:
Noise level of 85 decibels or more has been defined excessive by the OSHA, and according to OSHA, the humans are required to have hearing protection when they are exposed to sound level of 85 dB or more for 2 or more than 2 hours.
OSHA’s Permissible Noise Exposures :
Occupational Safety & Health Administration (OSHA) has specified some permissible noise exposures according to different times our ears are exposed to them.
Final Verdict:
Hearing protection is very important if you want to protect your ears from permanent damages, there are multiple options available for you to protect hears from excessive noise and hearing lose problems. For example, you can use some of the best earplugs for your ears or can pick earmuffs too.
| Duration Per Day (Hours) | Sound Level (dBA) |
|---|---|
| 8 | 90 |
| 6 | 92 |
| 4 | 95 |
| 3 | 97 |
| 2 | 100 |
| 1.5 | 102 |
| 1 | 105 |
| 0.5 | 110 |
| < 0.25 | 115 |
Final Verdict:
Hearing protection is very important if you want to protect your ears from permanent damages, there are multiple options available for you to protect hears from excessive noise and hearing loss problems. For example, you can use some of the best earplugs for your ears or can pick earmuffs too.