Hearing Protection
Determining the need to provide hearing protection for employees can be challenging.
Employee exposure to excessive noise depends upon a number of factors, including:
- The loudness of the noise as measured in decibels (dB).
- The duration of each employee's exposure to the noise.
- Whether employees move between work areas with different noise levels.
- Whether noise is generated from one or multiple sources.
Generally, the louder the noise, the shorter the exposure time before hearing protection is required. For instance, employees may be exposed to a noise level of 90 dB for 8 hours per day (unless they experience a Standard Threshold Shift) before hearing protection is required. On the other hand, if the noise level reaches 115 dB hearing protection is required if the anticipated exposure exceeds 15 minutes.
The table below shows a sample of the permissible noise exposures that require hearing protection for employees exposed to occupational noise at specific decibel levels for specific time periods.
Sample Permissible Exposure Levels
| Duration per Day | Sound Level in dB* |
|---|---|
| 8 hours | 90 |
| 4 hours | 95 |
| 1 hour | 105 |
| 15 minutes or less | 115 |
*When measured on the A scale of a standard sound level meter at slow response. Source: 29 CFR 1910.95, Table G-16.
Some types of hearing protection include:
- Single-use earplugs are made of waxed cotton, foam, silicone rubber or fiberglass wool. They are self-forming and, when properly inserted, they work as well as most molded earplugs.
- Pre-formed or molded earplugs must be individually fitted by a professional and can be disposable or reusable. Reusable plugs should be cleaned after each use.
- Earmuffs require a perfect seal around the ear. Glasses, facial hair, long hair or facial movements such as chewing may reduce the protective value of earmuffs.
Attenuation
If engineering and work practice controls do not lower employee exposure to workplace noise to acceptable levels, employees must wear appropriate hearing protection. It is important to understand that hearing protectors reduce only the amount of noise that gets through to the ears. The amount of this reduction is referred to as attenuation, which differs according to the type of hearing protection used and how well it fits.
Action Level
Manufacturers of hearing protection devices must display the device's NRR on the product packaging. If employees are exposed to occupational noise at or above 85 dB averaged over an eight-hour period (the action level), the employer is required to institute a hearing conservation program that includes regular testing of employees' hearing by qualified professionals.
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1-7. At what level of exposure to occupational noise over an eight-hour period, must employers institute a hearing conservation program?
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