When should noise dosimeters or sound level meters be used to measure exposure?
A sound level meter such as SV 973 measures sound level at a single point in time, which is useful when sound is steady‑state with little variation in level. But when sound exposures vary in level and duration, it’s difficult to accurately estimate exposure using a sound level meter. A noise dosimeter such as SV 104A should be used instead.
Exposure monitoring with noise dosimeters
A noise dosimeter measures sound levels continuously over time and integrates them into a single value, the noise dose. A dosimeter provides a more accurate estimate of noise exposure when sound levels fluctuate and/or exposure durations vary, and can alert the user in real-time to the need for hearing protection based on the accumulated noise dose. Noise dosimeters are easy to operate and can be used for a wide variety of applications. Therefore, it is the preferred method following ISO 9612.
When should Class 1 Sound Level Meters be used?
The ISO 9612 recognizes handheld sound level meters as well as personal noise dosimeters. Noise dosimeter, meeting IS0 61721 and IEC 61672-1 standard, is the preferred device. In case of measurements in low temperatures or when noise is dominated by high frequencies, the class 1 instruments such as SV 971A are recommended.
Noise dosimeters calibration and periodic verification
Noise dosimeters should be calibrated before and after each series of measurements. Additionally, they should be verified in the accredited laboratory at least once every 2 years.