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MICROPHONE SPECTRUM TEST

Inspect the frequency content your browser receives from a microphone. The test draws a live FFT spectrum, estimates the strongest frequency bin, shows relative digital input level and can capture a three-second quiet-room baseline.

LOCAL MEDIAAudio is analyzed in this page and is not recorded or uploaded by the diagnostic.
Private local diagnostic

Frequency spectrum & relative noise floor

MICROPHONE OFF
50 Hz250 Hz1 kHz4 kHz10 kHz+

How to use the microphone spectrum

  1. Start the analysis and choose the microphone in your browser permission prompt.
  2. Speak, clap softly or play a reference tone near the microphone and watch the frequency distribution change.
  3. For a quiet baseline, stop speaking and reduce nearby noise, then run the three-second capture.
  4. Repeat after changing gain, microphone position, USB port or input device to compare relative behavior.
  5. Stop the microphone when finished; the page releases the media track and AudioContext.

What dBFS means here

The relative level is calculated from the digital waveform received by the Web Audio API. 0 dBFS is the top of the digital scale; normal microphone signals appear as negative values.

This is not dB SPL and is not a calibrated measurement of physical sound pressure. Microphone gain, AGC, drivers and browser processing can change the digital level.

Dominant-frequency estimate

The page identifies the strongest FFT bin above very low-frequency/DC content. It is useful for visual comparisons and steady tones, but room reflections, noise, harmonics and microphone response can move the strongest bin.

Quiet baseline

The three-second baseline averages the page's relative RMS level while you keep the environment quiet. Use it to compare changes on the same device/setup, not to claim an absolute acoustic noise-floor specification.

Browser processing can matter

This tool requests echo cancellation, noise suppression and automatic gain control disabled where the browser honors those constraints. Some platforms can still apply processing outside the page's control.

Privacy and limitations

  • No recording file is created by this diagnostic.
  • No spectrum or waveform data is uploaded by the tool.
  • The browser/OS chooses the actual input path and can apply processing.
  • FFT resolution depends on sample rate and analyser size.
  • It cannot replace a calibrated measurement microphone and audio analyzer.

Microphone spectrum FAQ

Why is the dominant frequency jumping around?

Speech and room noise contain many frequencies that change constantly. A steady tone gives a more stable peak than normal conversation.

Why is my quiet baseline different after reconnecting?

Input gain, automatic processing, device selection or environmental noise may have changed. Treat the baseline as a relative comparison within the same setup.

Does this page hear or save my voice?

The browser provides the live stream to local Web Audio nodes. The diagnostic does not create or upload an audio recording.