Noise Reduction Ratings Explained

Noise Reduction Rating (NRR) is the measurment, in decibels, of how well a hearing protector reduces noise as specified by the Environmental Protection Agency. The higher the NRR number the greater the noise reduction. When dual protectors are used, the combined NRR provides approximately 5 - 10 decibels more than the higher rated of the two devices. For example, using disposable ear plugs (NRR of 29 decibels) with ear muffs (NRR 27) would provide a Noise Reduction Rating of approximately 39 decibels.

The amount of on-the-job noise exposure can be determined through various testing devices. Excessive noise is defined as 85-90 decibels or more over an 8 hour period.

Examples of noise levels considered dangerous by experts are a lawnmower, a rock concert, firearms, firecrackers, headset listening systems, motorcycles, tractors, power tools and industrial machinery. All can deliver sounds over 90 decibels and some up to 140 decibels.

Painful:
150 dB = Rock Concerts at Peak
140 dB = Firearms, Air-Raid Siren, Jet Engine
130 dB = Jackhammer
120 dB = Jet Plane Take-off, Amplified Music at 4-6 ft., Car Stereo, Band Practice

Extremely loud:
110 dB = Machinery, Model Airplanes
100 dB = Snowmobile, Chain saw, Pneumatic Drill
90 dB = Lawnmower, Shop Tools, Truck Traffic, Subway

Very loud:
80 dB = Alarm Clock, Busy Street
70 dB = Vacuum Cleaner
60 dB = Conversation, Dishwasher

Moderate:
50 dB = Moderate Rainfall
40 dB = Quiet room

Faint:
30 dB = Whisper, Quiet Library