How to Calibrate a Sound Level Meter

By Jerry Garner
Soundwaves, a sound level meter
Sound image by Alexander Sabilin from

A sound meter is used to measure sound pressure levels and mainly used in studies of noise pollution to quantify noise. This mainly applies to heavy industrial areas, noise from air planes and the environment. It used to measure sound levels in decibels (db). Modern sound meters also contain an LCD screen with digital readouts of the sound decibels, making it easier for a technician to pinpoint a specific sound level. Having a perfectly calibrated level meter is important for obtaining precise reading, making calibration the first and most important step in the process.

Place a new battery into the battery compartment of the meter. It has to be a new or reliable battery, as the sound meter's readings depend on it. Using old or weak batteries may result in inaccurate readings and results. Place the battery compartment cover back while holding the battery in place and tighten the screw to secure.

Turn on the calibrator and then choose the appropriate frequency weighting. The A -- frequency in the meter is meant to read sounds in residential areas as it is in the range of sound that the human ear can hear. Switch the frequency to either C or B if you wish to record loud noises and ones with low frequencies.

Take the external calibrator and rotate it so that it faces the microphone of your sound level meter. Turn the calibrator on and check the meter to see if an equal level or one that's close to the external calibrator's output level is showing. If this isn't the case, it's best to re-tune the whole device, but before resorting to that extreme, check to see if the device has a faulty battery.

Calibrate the sound level meter's response time. This determines how fast the meter will respond to differentiations in sound levels. It is recommended to switch to 200 ms if you want a quick response time, or 500 ms for a slower response time, which is ideal for noises with sounds that occur regularly.

Measurements can now be taken by simply pointing the microphone in the meter to the source of noise. It will then display the values and readings immediately on its LCD screen.


About the Author

I am also the publisher of, and hold a position at the local newspaper.