Noise dosimeter

A noise dosimeter (American) or noise dosemeter (British) is a specialized sound level meter intended specifically to measure the noise exposure of a person integrated over a period of time; usually to comply with Health and Safety regulations such as the Occupational Safety and Health (OSHA) 29 CFR 1910.95 Occupational Noise Exposure Standard or EU Directive 2003/10/EC.

Noise dosimeters measure and store sound pressure levels (SPL) and, by integrating these measurements over time, provide a cumulative noise-exposure reading for a given period of time, such as an 8-hour workday. Dosimeters can function as personal or area noise monitors. In occupational settings, personal noise dosimeters are often worn on the body of a worker with the microphone mounted on the middle-top of the person’s most exposed shoulder.

Area monitoring can be used to estimate noise exposure when the noise levels are relatively constant and employees are not mobile. In workplaces where employees move about in different areas or where the noise intensity tends to fluctuate over time, noise exposure is generally more accurately estimated by the personal monitoring approach.

Dosimeters are also used to collect data for use in legal proceedings, development of engineering noise controls, and other industrial hygiene purposes. When planning to conduct noise exposure measurements, steps must be taken to ensure that the dosimeters are calibrated and operated according to manufacturers’ specifications. It is also necessary to understand the properties of the acoustic environment, the main measurement objectives as they relate to determining the risk to hearing damage, and the limitations associated with the use of dosimeters. Dosimeter manufacturers recommend that the instrument be calibrated with an acoustical calibrator such as a pistonphone before and after each measurement to verify reliable operation. In addition to field calibration routines, the manufacturers recommend periodic comprehensive calibration and certification of the instrument by an accredited laboratory using traceable reference sources. Field calibration of contemporary dosimeters has been mostly automated through PC-based programs that run the calibration routine, document the time and date, and adjust for any offset in levels.

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