Noise Reduction Rating (NRR) 2 : The difference between the overall C-weighted sound level of a noise spectrum having equal energy per octave and the resulting A-weighted noise levels under a hearing protection device
Grainger, Inc. (Maintenance, Repair and Operating MRO), Glossary of Safety Terms, IL, USA 2012. www.grainger.com/images/GlossaryofSafetyTermsPDF.p df, (IndS/Maint, Repr and Opr - Amer) {79}