Noise Survey Instruments
Basically, 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.
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.
A dosimeter is like a sound level meter except that it stores sound level measurements and integrates these measurements over time, providing an average noise exposure reading for a given period of time, such as an 8-hour workday.
Dosimeters can be used to:
- Make compliance measurements according to OSHA’s noise standard.
- Measure the employee’s exposure to noise and automatically compute the necessary noise dose calculations.
With a dosimeter, a microphone is attached to the employee’s clothing and the exposure measurement is simply read at the end of the desired time period. A reader may be used to read out the dosimeter’s measurements. Since the dosimeter is worn by the employee, it measures noise levels in those locations in which the employee travels.