Renders a time-frequency heatmap of your file — brighter areas mean more energy at that frequency and moment — using a real short-time Fourier transform, not a decorative approximation.
The Audio Spectrogram turns sound into a picture: time runs left to right, frequency bottom to top and brightness shows level. It reveals things you cannot see in a waveform — hum, bird songs, vowels, harmonics, clicks, lossy-codec cutoffs and edits.
Choose from four colour maps, a logarithmic or linear frequency axis, up to 8192-point resolution and image widths up to 2800 px, then download the picture as a PNG.
The audio is mixed to mono and a short-time Fourier transform is computed with Hann-windowed frames (hop = size/4 or wider for long files). Each bin’s magnitude is converted to dB, mapped onto the dynamic-range window you choose below the brightest value, and coloured with a look-up table (Magma, Viridis, Ice or grayscale). The log axis maps pixels to frequencies between 30 Hz and the top frequency exponentially, which matches pitch perception.
Spot edits, clicks and codec cutoffs.
See harmonics and structure.
Visualise formants.
Find bird calls and insects.
| Resolution | 1024–8192 FFT |
|---|---|
| Axes | Log or linear frequency |
| Colours | Magma, Viridis, Ice, Gray |
| Export | PNG up to 2800 px wide |
A time-frequency picture of sound.
Each sustained pitch and its harmonics appear as stacked lines.
Rendering a full spectrogram for a very long file means processing and drawing an enormous number of data points — capping analysis keeps the tool fast and responsive. Trim your file first with the Audio Cutter if you need a spectrogram of a specific later section.
It's computed from a genuine short-time Fourier transform (STFT) of your actual audio data — the same underlying technique used in professional audio software, not a stylized animation.
This tool runs entirely in your browser using the Web Audio API. Nothing is uploaded, stored or shared — there is no server to send your file to, so it works offline once the page has loaded.
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