Noise Reduction Rating (NRR)

Last updated: February 25, 2021

What Does Noise Reduction Rating (NRR) Mean?

Noise reduction rating (NRR) is a system of classifying decibel (dB) levels of a distinct environment where ambient noise or intensity of sound is measured in graduated values. The American National Standards (ANS) is the authoritative organization that approves all hearing protection devices in line with Occupational Health and Safety Administration (OSHA) guidelines.


WorkplaceTesting Explains Noise Reduction Rating (NRR)

The noise factor in an environment can have detrimental impact on hearing over a protracted length of time. Although earplugs and/or earmuffs are designed to mitigate noisy surroundings, a common misconception is that the NRR dB number can reduce the loudness of sound by the variable amount on the label. For example, earplugs with a NRR 33 dB value will not decrease sound to 67 dB if the ambient noise of the environment is 100 dB.

Hearing products have different NRR noise reduction capacities, which can be used selectively to accommodate conditions that often depend on the source and duration of noise exposure. The workplace can cause hearing impairments to employees where frequent and excessive noise from manufacturing processes is persistent. Individuals who handle heavy equipment/machinery on a regular basis are more susceptible to hearing loss over time.

OSHA sets the precedent for identifying noise-generating machines and products, assigning sound dB levels coinciding to time duration intervals to deter overexposure. If NRR equipment falls below the benchmark, then alternative programs to preserve hearing must be introduced.


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