Microphone Spectrogram
See your microphone input as a real-time spectrogram. The browser's FFT splits sound into hundreds of frequency bands so you can read voice formants, music harmonics, whistles, and noise — all without sending audio anywhere.
Live spectrogram from your microphone.
Audio stays in your browser. Nothing is sent or recorded.
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How a spectrogram works
A microphone records pressure-vs-time. A Fast Fourier Transform (FFT) converts a short window of that signal into a magnitude-per-frequency snapshot. Stack snapshots side by side, colour the magnitude, and you get a spectrogram — time on the x-axis, frequency on the y-axis, brightness as loudness.
The browser's AnalyserNode does the heavy lifting locally — no audio is sent over the network. This tool runs with an FFT size of 2048, smoothing 0.6, and a 1-pixel-per-frame scroll, giving roughly 60 frames per second of scrolling.
What you'll see
| Sound | Shape on the spectrogram |
|---|---|
| Whistle | A single narrow horizontal band that slides as the pitch changes. |
| Voiced vowel | A fundamental plus stacked harmonics every multiple, with two or three darker bands (formants) that identify the vowel. |
| Sibilants (sh, s, f) | Broad noise in the high frequencies (5–10 kHz), no harmonic structure. |
| Music chord | Several harmonic stacks at different fundamentals, lining up vertically. |
| Clap | A vertical bright line — broadband energy in a single moment. |
Linear vs. logarithmic frequency
Pitch is logarithmic — doubling the frequency raises the note by exactly one octave. The default log axis spaces octaves equally, so voice and music look natural. Turning it off gives a linearaxis: useful for inspecting noise floors, ultrasonic chirps, and engineering signals where equal Hz steps matter.
Privacy & permissions
The browser will ask for microphone permission once. Audio is processed entirely on your device via the Web Audio API; nothing is uploaded, recorded, or shared. Press Stop microphone at any time to release the audio stream — the indicator in your browser chrome will disappear.