When establishing a hearing conservation program, safety professionals need to decide on whether to provide earplugs or earmuffs in order to reduce employee exposure to noise. There are advantages and disadvantages for both. One way to judge hearing protectors is to use the Noise Reduction Rating (NRR). Disposable plugs have the highest rating up to 33 NRR while the reusable ones usually rate between 25 and 27 NRR. Earmuffs have ratings from the low 20s to 30 NRR. Usually the the bigger the muff the higher the rating.
Noise Exposure = Noise Level (dBA) – (NRR-7)
The problem with using the NRR is that they are done in the laboratory and may not reflect actual employee exposure. Employees may not properly insert plugs into the ear canal and muffs may not properly seal on the ear due to glasses or sweat grease, and grime. Because of the discrepancy between lab and the field, OSHA recommends a 50% correction factor. It also suggests that the use of plugs and muffs may provide an additional 5 decibels of protection. So there is no clear winner. Employee preference may be the best choice, since if they choose one they like they will probably wear them.