What this test can tell you
The meter displays browser microphone samples as digital dBFS levels with smoothing, sampled minimum and maximum, an energy average and a 60-second graph. An optional reference reading adds an offset for your current setup.
The tool cannot infer physical sound pressure from an arbitrary microphone. A one-point reference is not frequency calibration, A-weighting, exposure assessment or certification. Gain and device processing can change the readings.
How to use it
- Press “Start decibel meter” and allow microphone access.
- Select the microphone and keep its position and input gain unchanged while comparing sounds.
- Read the digital dBFS level. Zero dBFS is the digital ceiling; negative values are below it, not negative physical sound pressure.
- For an adjusted estimate, play a steady sound and measure it with a reference meter at the same position. Enter that reading and press “Set reference from current sound”.
- Reset values before comparing another interval, and recalibrate if you change the microphone, gain or processing.
Why a microphone needs a reference
A browser receives digital samples, not the microphone sensitivity needed to determine sound pressure. There is no universal dBFS-to-dB-SPL offset for phones and laptops. Before a reference is set, this tool reports dBFS. A reference sets one additive offset for the current microphone, gain and sound. It does not validate other frequencies or levels.
What the numbers mean
The live display smooths mean-square samples over approximately 125 ms. The average combines equal-time samples by energy rather than taking a simple arithmetic mean of dB values. The maximum is the highest sampled smoothed level, not a true acoustic peak. The tool adds no A-weighting and does not report certified dB(A), exposure or noise dose.
Not working? Try these fixes
The value does not change
Make sure the right microphone is selected and that no other app is using it. On Windows and Mac, allow microphone access for your browser in the system privacy settings, then reload the page.
The reading seems too low or too high
Clear the reference if you changed microphones or input gain. Compare the same steady sound at the same position with a reference meter. Automatic gain and other device processing can still change the result.
iPhone: the level barely moves
Safari can apply its own audio processing. Hold the phone with the bottom microphone towards the sound and avoid covering it with your hand or a case.
Frequently asked questions
Is my audio recorded or uploaded?
No. The level is calculated in your browser from the live microphone signal. Nothing is recorded or sent to a server.
Can this tell me whether a sound is safe?
No. Digital levels and a one-point reference adjustment cannot establish safe noise exposure. Use an appropriate calibrated instrument and qualified guidance for hearing protection or workplace assessments.
Can I use this decibel meter for a noise complaint?
It can show changes in the signal received by your microphone, but it does not provide certified sound-pressure measurements or legal evidence.
Why do two phones show different values?
Microphone sensitivity, input gain and device processing differ. Without an external reference, a digital dBFS reading cannot be compared with a physical sound-pressure value.