Personal Attenuation Ratings (PAR’s) are designed to give specific attenuation data for an individual. These are done with any non-custom or custom-fit product line and give an evaluation of how well a hearing protector is working. Due to some individuals, a PAR rating can very quite a bit due to poor fit, incorrect use, and/or improper installation. However, with properly made “custom-fit” items, the PAR rating is more accurate and usually higher then anything generically fit, or used.
A Noise Reduction Rating (NRR) is a rating given by a certified lab in regards to an “overall” test group that was scored and recorded to come up with an “average” rating for a hearing protector. It is a common number you will see on packaging for disposable and off-the-shelf hearing protection items.