Sound Level Meters

Sound level meters and noise dosimeters are used in many kinds of sound and noise analysis including industrial safety, traffic and transportation noise quantification, and scientific noise measurement. They are frequently hand-held and battery-powered. Sound level meters measure real-time sound and can have functions such as signal analysis, noise dose measurement, and different time and frequency weighting. Sound level meters and noise dosimeters are used for measuring Sound Pressure Level (SPL) and different weightings such as A-weighted SPL, C-weighted SPL, Sound Exposure Level, etc. Noise dosimeters are used for specific measurement capability for defined industrial safety criteria. A typical measure is a sound exposure for an 8-hour period. These instruments can be found either individually or as one unit that covers the capabilities of both products.

Two critical specifications for sound level meters and noise dosimeters are frequency range and sound level range. Frequency Range is the range of frequencies for which the meter maintains a constant sensitivity within defined boundaries. Functionally, this is the operational range of the meter. The sound level range is limited on the low end by the inherent noise of the acoustic system and on the high end by the maximum sound pressure level. Many sound level measurement modes are available for these devices. Flat or unweighted SPL measures the straight physical quantity with no weighting. A-weighting is a frequency domain weighting based on human hearing response. This filters out low-frequency sound to approximate the response of the human ear. C-weighting filters less low-frequency sound than A-weighting, providing a closer representation of acoustic energy across all frequencies. A-weighted sound exposure level measurement is used for short or one-time sounds as the equivalent 1-second level. Equivalent continuous SPL is the noise level of a continuous steady sound whose time-averaged power equals that of the fluctuating noise under measurement. Percentile SPL measures the percentage of time during a given measurement period that the instantaneous measurement exceeds a given value.