What Is a Sound Level Meter?
This tool reads your real microphone input through the Web Audio API and calculates a live relative sound level from it, shown as a percentage bar rather than a calibrated decibel figure. It's genuinely useful for comparing quiet versus loud moments, checking that your microphone is picking up sound at all, or watching how your input level responds as you speak at different volumes - but it deliberately does not claim to be a real dB SPL meter, because a browser has no way to produce one.
How to Use the Sound Level Meter
- Choose your microphone or leave System default microphone selected. Select Browser default processing, or request processing OFF if you want to inspect the more direct microphone signal (your browser may override this setting).
- Click Start Meter and grant microphone permission. Use HTTPS or localhost; the live microphone indicator confirms when input is running.
- Speak or make a sound near the mic. Watch the Relative Level bar and the original Quiet/Normal/Loud signal zones. These are arbitrary relative input categories, not real-world sound-safety levels.
- Read RMS dBFS for average digital signal energy and Instant Peak dBFS for the loudest sample in the current window. Session Max Peak keeps the highest sampled peak until cleared. These values are not dBA or calibrated dB SPL.
- Use the Waveform and Digital Level History charts to spot changes over time. Average RMS, P95 RMS and near-full-scale frame counts provide extra context but do not diagnose microphone hardware faults.
- Optionally click Quiet Baseline · 3s while the room is quiet. This stores a digital baseline for comparisons on the same microphone with unchanged gain and processing.
- Click Export CSV to save the latest 600 numeric measurements, or Clear Statistics to start a fresh comparison. Audio itself is never recorded or uploaded.
- Click Stop & Release Mic when finished. The microphone is also released if you switch away from the tab or leave the page.
How It Works
This tool connects your microphone stream to a Web Audio AnalyserNode, which provides raw
time-domain amplitude data many times per second. From that data, it calculates the root-mean-square (RMS)
value - a standard way of representing the average energy of an audio signal - and scales it into a
percentage for the bar display. This is a genuine, real-time calculation from your actual microphone input,
not a placeholder or randomized animation.
Understanding Your Results
- Bar rises and falls in step with actual sound in the room - your microphone is capturing input correctly and the meter is responding to real audio.
- Bar stays near zero even when you speak clearly at normal volume - check your microphone's input gain in your operating system's sound settings, or confirm the correct device is selected as default input.
- Bar maxes out even in a quiet room - could indicate excessive input gain applied at the OS or driver level; try lowering microphone sensitivity in your system sound settings.
- Peak value from this session - a simple reference point for the loudest moment detected, useful for comparing different rooms or positions relative to each other.
Browser Limitations
This meter cannot report an actual, calibrated decibel (dB SPL) value the way a dedicated sound level meter or phone app with a calibrated microphone can. Microphone sensitivity, gain settings, and hardware quality vary enormously between devices, and browsers have no access to a microphone's absolute acoustic calibration data - so the same real-world sound can produce very different percentage readings on different microphones. This tool is best used to compare relative changes on the same device, not to compare absolute loudness between different devices or rooms.
Common Mistakes to Avoid
- Comparing readings between two different microphones as if they were calibrated - different microphones and gain settings will show very different percentages for identical real sound.
- Assuming this replaces a real decibel meter - for workplace noise compliance, hearing safety thresholds, or any application needing an actual dB SPL number, use a calibrated instrument or phone app designed and tested for that purpose.
- Forgetting to stop the meter - the microphone stays active while the meter runs, so stop it when you're finished to release access.
Frequently Asked Questions
Is this the same as a real decibel (dB) meter?
No. This shows a relative percentage level calculated from your microphone's raw signal, not a calibrated dB SPL value - browsers cannot access the calibration data needed for that, and microphone sensitivity varies too much between devices for an absolute reading to be meaningful.
Why does the same sound register differently on my phone versus my laptop?
Microphone sensitivity and gain handling differ significantly between devices, so this relative meter will naturally show different percentages for identical sound on different hardware.
Is my audio recorded or saved during this test?
No. Audio is analyzed live in memory to calculate the level and is never recorded, saved, or transmitted anywhere.
Can I use this to check if my microphone is muted?
Yes - if the bar stays completely flat even with loud sound nearby, check whether your microphone is muted at the hardware, OS, or app level.
Does stopping the meter turn off my microphone?
Yes, clicking "Stop Meter" closes the audio context and releases the microphone stream completely.
Conclusion
For a quick, live sense of relative sound level - quiet versus loud, working versus muted - this meter gives you a genuine real-time reading from your own microphone. For a fuller check of your microphone's overall quality and frequency response, follow up with the Microphone Tester.