LIVE SOUND METER / GUIDE & INFORMATION
Accuracy & calibration
Understand what the estimate means, align it to a reference, and check the errors that matter for your setup.
Why an uncalibrated number can be wrong
A browser receives digital microphone samples, not a calibrated sound-pressure measurement. Microphone sensitivity, input gain and device processing affect the number. The default 100 dB offset is a display convention, not a measured sensitivity. Absolute readings can be substantially wrong.
Without a reference instrument, keep the same device and settings and use the meter to compare changes. Do not force a quiet room or conversation to match a value from an example chart.
Align with a trusted reference meter
Use an A-weighted sound level meter and a steady source. Allow the source to settle, then follow these steps:
- Put both microphones close together without blocking either. Keep their distance and orientation fixed.
- Measure for 30–60 seconds. Avoid changing the source level while comparing the readings.
- Open Microphone & advanced options, choose Calibrate and enter the reference meter’s average.
- Save the alignment, then repeat the comparison at another moderate level. Investigate any large disagreement instead of assuming one match proves accuracy.
What the saved alignment changes
The tool uses the most recent 10 seconds of captured energy, or the available shorter sample of at least 5 seconds, to calculate one offset. That offset affects the entire current session and is saved for the same browser, input device ID, sample rate and weighting.
Reset calibration to remove it. Recheck after changing microphone, input gain or audio-processing settings; clearing browser storage or a changed device ID can also remove the saved match. A one-point alignment cannot correct uneven frequency response or a clipped signal.
If a result looks unexpected
Check the setup before adjusting calibration. An offset cannot repair the problems below.
| What you notice | What to check |
|---|---|
| The reading changes when you pick up the device | Set it down; avoid handling noise and a covered microphone. |
| A fan produces large changes close to the microphone | Keep airflow off the microphone and keep the distance fixed. |
| Louder sounds barely change the reading | Check the selected input, system gain, processing warnings and clipping. |
| Repeated runs disagree | Check for changing background activity, source settings and microphone position. |
Know when to use another instrument
This tool has not been certified against IEC sound level meter classes. Use appropriate calibrated equipment and competent procedures for workplace compliance, medical or legal decisions. For an everyday before-and-after comparison, use the repeatable measurement workflow below.
Last reviewed October 22, 2026