Hearing protectors are designed to prevent hearing loss from exposure to high level noise. They are rated for the amount of attenuation or sound blockage and given an NRR noise reduction rating. The rating, however, is only an estimate and does not guarantee the exact level of protection in the real world.
The Occupational Safety and Health Administration OSHA recognize that the amount of noise reduction can vary significantly depending upon a number of factors, including improper placement of a protector. Accordingly, OSHA Regulation 29 CFR 1910.95(j)(1) recommends attenuation measurements of a worker's hearing protector to determine the adequacy of that device for the worker's environment.
Determine your daily noise dose
Step 1
Turn on the noise dosimeter badge and press the calibration button to initiate auto-calibration.
Step 2
Clip the badge or the microphone of the badge to an area close to your ear, such as the shoulder. Be sure that it will not encumber movement or make contact with machinery.
Step 3
Press the start or run button to begin measuring the noise levels in your work areas for an entire work day.
Step 4
Remove the dosimeter at the end of the work day, connect it to your computer to download the data, and read out the results.
Your daily noise dose is the overall time-weighted, decibel dBA level of noise that you are exposed to for an eight hour work day.
Measure hearing without and with earplugs
Step 1
Select and click on the hearing test application in the computer to begin your hearing test.
Step 2
Place the headphones over your ears and indicate when you hear a tone with the response button or response key on the computer keyboard. The software program will automatically test your hearing from 500 Hz to 4000 Hz frequencies.
Step 3
Insert one or both earplug hearing protectors as directed by the computer program.
Step 4
Repeat Step 2 and Step 3 to measure your hearing with the ear plugs.
Calculate real ear attenuation
Step 1
Subtract the unplugged hearing levels from the earplug hearing levels at each frequency to determine the amount of attenuation.
For example, at 500 Hz subtract 15 dB (unplugged value) from 35 dB (plugged value). The difference indicates that you get 20 dB of attenuation or noise blockage at 500 Hz.
Step 2
Add the attenuation values for each frequency and divide the sum by the number of frequencies tested. The resulting single number is the personal attenuation rating or PAR for your hearing protector.
Step 3
Subtract the PAR from the sound level noise dose in Section 1, Step 4. This is the real ear attenuation of your hearing protector for your work environment.
According to the National Institute for Occupational Safety and Health, the attenuation level should be less than 85 dBA.
Tips and Warnings
- Consult with the hearing conservation personnel at your workplace to determine whether your hearing protectors meet OSHA criteria for your job. You may need training or different protectors.
- Noise induced hearing loss is permanent but can be prevented with proper training and consistent use of your hearing protectors.
Things You'll Need
- Noise dosimeter badge
- One pair of earplug hearing protectors
- Laptop or desktop computer
- Calibrated headphones
- Response button
- Real ear attenuation measurement software
- Real ear attenuation measurement sound generator
- Quiet room
References
- Occupational Safety & Health Administration: Regulation 29 CFR 1910.95
- Center for Disease Control National Institute for Occupational Safety and Health: NIOSH Publication No. 98-126: Criteria for a Recommended Standard: Occupational Noise Exposure.
- "The Hearing Review": Fit-Testing of Hearing Protection.
