Noise Survey Instruments
There are two different instruments to measure noise exposures: the sound level meter and the dosimeter.
Sound Level Meter (SLM)
A sound level meter is a device that measures the intensity of sound at a given moment.
Since sound level meters provide a measure of sound intensity at only one point in time, it is generally necessary to take a number of measurements at different times during the day to estimate noise exposure over a workday. If noise levels fluctuate, the amount of time noise remains at each of the various measured levels must be determined.
A sound level meter typically consists of a microphone, a calibrated attenuator, a stabilized amplifier, an indicating meter, and the designated weighting networks. Two types of SLMs are commonly used in the workplace:
Type 1 SLM. The Type 1 meter has an accuracy of +1 dBA and is preferred for the design of cost-effective noise controls.
Type 2 SLM. A Type 2 meter is has an accuracy of +2 dBA and meets the minimum requirement by OSHA for noise measurements. It is usually sufficient for general purpose noise surveys. It is usually less bulky, lighter, and less expensive than the Type 1 SLM.
Sound level meters can be used to:
- Spot-check noise dosimeter performance.
- Determine the employee's noise dose whenever use of a noise dosimeter is unavailable or inappropriate.
- Identify and evaluate individual noise sources for abatement purposes.
- Aid in determining the feasibility of engineering controls for individual noise sources.
- Evaluate hearing protectors.
Please click here to learn more about the considerations of use for sound level meters.
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2-4. Which sound level meter meets minimum OSHA standards but is less accurate?
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