Why and How to Use a Noise Dosimeter

Extremely loud noises can damage hearing, but so can lower-decibel noises over time.

Construction sites aren’t quiet. And while even brief exposure to extremely loud equipment — think jackhammers and nail guns — can permanently damage hearing, so can exposure to lower decibels over longer periods time. That’s where a noise dosimeter comes into play.

These small devices can be worn by workers to help ensure they’re not exposed to damaging levels of noise over the course of a shift.

Occupational Safety and Health Administration (OSHA) guidelines require workers' noise exposure be limited to 85 decibels as an 8-hour time weighted average. While a handheld sound level meter can tell you the noise level of a particular piece of equipment at a particular moment (and help you spot-check the performance of a noise dosimeter), a noise dosimeter can reveal information on overall noise exposure during a shift or task — and tell you whether or not you’re in compliance.

Here are the basics on how to use one.

1. Set it up per OSHA criteria. You’ll need to set the device to a criterion level of 85 dB. In addition, OSHA has other rules for set-up, described in this OSHA Technical Manual.

Calibrate the device before using it and make sure the batteries are fresh enough to last the whole testing period.

2. Affix the device and microphone to the worker. Attach the noise dosimeter clip to the worker's belt and the microphone to his or her shoulder or lapel. Make sure the microphone won't be covered by shirt material and that it points straight up. To keep the wire between the microphone and the unit from getting caught on an object, try to run it underneath the worker's clothing. According to OSHA, “The dosimeter can hang inside the outer layer of clothes as well (an advantage in wet weather), but the microphone must remain in the open air without contacting other surfaces (except the base on which it clips).”

3.  Use a windscreen outdoors. These are sensitive instruments; the microphone should be protected from the elements with a windscreen. Some models include one, but they’re also available as accessories.

4.  Evaluate the results. The noise dosimeter will provide the average noise level for the recording time. If that time is less than a full shift, many models can project what that level over the whole shift would be. If the exposure is too high, it’s time for some hazard abatement and control measures.