Sound level meter for noise in decibels

The A/C/Z frequency weighting here matches IEC 61672 to better than 0.1 dB. The absolute level is another matter: it depends on your microphone's sensitivity and on the input gain your system adds on top, and the browser reports neither. On Windows the microphone level slider alone moves every reading by up to 30 dB, which is why an uncalibrated meter usually reads too high rather than too low. The line under the number says whether the meter is calibrated. Calibrating by silence takes 5 seconds and brings readings to within about ±7 dB; calibrating against another meter is more accurate still. For professional or legal measurements, use a certified sound level meter.

Recordings include date and time in the filename for documentation. While browser recordings alone may not meet legal standards, they can support noise complaints as supplementary evidence. Consult local regulations.

A-weighting adjusts the measurement to match human hearing sensitivity. Our ears are less sensitive to very low and very high frequencies. dBA is the standard for noise regulations and occupational safety.

NIOSH and the EU/UK rules both draw the line at 85 dB(A) averaged over an 8-hour day, and every 3 dB more halves the allowed time — at 100 dB(A) it is 15 minutes. OSHA (USA), Korea and Brazil count in 5 dB steps, so the same noise gets a longer allowance, and Russia sets 80 dBA. Choose your country under "Shift noise dose" and the warnings follow that standard.

Press “Calibrate” under the number. By silence: go to the quietest place you have, stay still and press the button — the meter listens for 5 seconds and takes a quiet room (about 35 dBA) as its reference. Against a reference: put a phone sound meter app or a hardware meter next to the microphone, turn on a steady noise such as a fan or running water, and enter the number it shows. The calibration is remembered for that microphone and is also used by the hearing test and the projector noise meter. Even without it, relative changes in dB are reliable.

Measure each typical task for a few minutes with the phone near the worker's ear, then list the tasks with their times under "Work out a shift by tasks" — the tool adds them up into LEX,8h or TWA and a dose for the standard you chose, the way the HSE exposure calculator does. One long measurement works too: the card projects it onto your shift length. A phone gives an estimate; a decision about a workplace needs a class 1 or 2 meter and a competent person.