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Mic Test Online: Noise Floor, Plosives & Sibilance

Free · No sign-up · Your audio never leaves your device

  1. Stay silent for 3 seconds, so the page can hear your room on its own.
  2. Say: “Peter Piper picked a peck of pickled peppers.”
  3. Say: “She sells seashells by the seashore.”
Live spectrum (bright line) and peak hold (thin line), 20 Hz to 20 kHz. Shaded: below 120 Hz, 200 to 500 Hz, and 4.5 to 10 kHz.
Noise floor (quietest 0.5 s)
–
Your room and preamp noise at this gain setting.
Signal-to-noise ratio
–
Loudest half second minus the noise floor.
Sample peak
–
0 dBFS is where the signal clips.
Peak below 120 Hz
–
Plosive blasts, handling noise and rumble show up here.
Strongest 200–500 Hz frequency
–
In the average spectrum of your voice, not the silent parts.
Sibilance peak (4.5–10 kHz)
–
Measured at your loudest S sound.

What does a mic test measure?

A mic test shows whether your microphone works and how clean its signal is. This one reads the raw input live, in dBFS. The noise floor is what the mic picks up when nobody speaks: room noise, fans and preamp hiss. Signal-to-noise is your voice level minus that floor. Plosives, the pops of P and B sounds, are measured below 120 Hz, and sibilance, the hiss of S sounds, between 4.5 and 10 kHz.

How it works

  1. Step 1

    Raw input

    The page asks the browser for your microphone with echo cancellation, noise suppression and automatic gain turned off, and tells you if the browser kept any of them on.

  2. Step 2

    Three bands are measured

    A 4096-point spectrum, plus two filtered copies of the signal: below 120 Hz for plosives and rumble, and above 4.5 kHz for sibilance. Levels are in dBFS, read from the audio samples.

  3. Step 3

    Readings build up

    The noise floor is your quietest 0.5 s, the voice level your loudest 0.5 s, and the sibilance frequency is taken at your loudest S sound.

Questions

Is my voice recorded or uploaded?

No. The audio is analyzed in this browser tab as it arrives and is not recorded, stored or sent anywhere.

What does dBFS mean?

Decibels relative to full scale. 0 dBFS is the loudest level a digital signal can reach before it clips, so every reading here is a negative number. Levels are RMS over half a second unless the card says peak.

Why turn off the browser's voice processing?

Browsers process the microphone for calls: echo cancellation, noise suppression and automatic gain. That changes your levels and hides room noise, so the page asks the browser to turn all three off and shows whether it did.

Why does my noise floor change when I change the input gain?

The input gain raises your voice and the noise together, so the floor in dBFS moves with it. The signal-to-noise ratio, your voice level minus the noise floor, is the number to compare between setups.

What does the demo signal do?

It feeds a synthetic signal into the analyzer so you can see how the page works without a microphone: quiet noise, a 70 Hz thump and a hiss around 6.8 kHz. Nothing plays through your speakers.

Privacy: what runs where

  • Microphone audio is analyzed in this browser tab as it arrives. It is never recorded, stored or uploaded.
  • The microphone turns off when you press Stop or leave the page.
  • Nothing is downloaded from anywhere else: the analyzer is part of this page.

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