Noise Reduction Rating (NRR) is a crucial indicator of a Hearing Protection Device’s (HPD) ability to reduce external noise levels and protect the user’s ears. It serves as a reference point for buyers seeking effective HPDs, with higher NRR ratings offering better noise reduction.
The concept of NRR was introduced by the U.S. Environmental Protection Agency (EPA) in the 1970s as part of their Noise Label Program. Since 1979, it has been mandatory for all HPDs sold in the USA to display the NRR on their labels. The EPA prescribed testing rules, conducted according to ANSI STD S3.19-1974 (revised in 2016), to ensure accurate results.
Any HPD manufactured after 1979 must have an NRR label. This includes ear muffs, disposable earplugs, and reusable earplugs—devices designed to reduce sound entering the ear.
NRR testing involves evaluating HPDs on ten trained human subjects under controlled conditions using nine test frequencies. The EPA may also independently test a device if necessary.
Knowing the NRR of your HPD is essential because it helps identify the appropriate level of noise protection. Noise-induced hearing loss can be irreversible and can occur from exposure to loud, unpleasant, or disruptive sounds. Around 22 million Americans are exposed to hazardous workplace noise each year.
Excessive noise is typically considered noise levels above 85 dBA for more than eight hours a day. To check noise levels at your workplace, use tools like the NIOSH Sound Level Meter app. Employers are required by OSHA to implement hearing conservation programs if noise levels exceed an 8-hour time-weighted average of 85 dBA. This may involve engineering controls or providing HPDs to employees for adequate protection.
Remember, noise-induced hearing loss can result from various factors, including exposure to chemicals, toxins, corrosive substances, and drugs. Protecting your ears with the right HPD, considering its NRR, is crucial to safeguard your hearing health effectively