Most health and safety professionals responsible for hearing loss prevention rely heavily on hearing protection devices (HPD) as a vital part of hearing conservation programs. One essential aspect of HPD selection and use is the noise reduction rating (NRR). According to 40CFR211, any device offered for use as a hearing protector in the U.S. must be evaluated and labeled with its NRR.
But where do these numbers come from, and what do they mean to today’s hearing conservationist?