microphone level test
This page reads your microphone audio with the Web Audio API and shows the level in real time, converted to decibels relative to the digital ceiling. Level analysis runs entirely on the local Web Audio API; the captured audio is never recorded or transmitted outside the browser.
Even in total silence the RMS never quite reaches zero, because the microphone itself and the analog to digital converter carry a residual electrical noise floor.
That -30 to -20 dBFS range is typical of speech picked up from close range without shouting, far enough from the 0 dBFS ceiling to avoid distortion.
Getting that close to 0 dBFS signals the signal is about to overrun the digital ceiling, producing the characteristic distorted cutoff of clipping.
No. The tool only analyzes instantaneous level to drive the meter; nothing is recorded or sent to a server. Stopping the microphone ends local capture.
Because the scale is dBFS, decibels relative to the system's digital ceiling, and 0 dBFS marks the maximum value audio can represent without distorting; since almost no real sound uses the entire ceiling, the normal reading lands below zero, as a negative number.
Because perfect electrical silence does not exist: the microphone itself, the preamplifier, and the computer's analog to digital converter all introduce a residual noise floor, so the calculated RMS never reaches exactly zero, even with no intentional sound being captured.
Because autoGainControl adjusts microphone gain automatically to keep volume inside a stable range; with it on, a naturally quiet microphone can end up looking similar to a loud one, so turning it off is necessary to see the real, unprocessed intensity of the signal.
It means the signal is close to the system's digital ceiling and at risk of clipping, the abrupt cutoff of the waveform caused by saturation, which produces audible distortion; at that point it is worth lowering the microphone's input gain before recording or transmitting.
Audio is analyzed locally for visual level; nothing is recorded or uploaded.