Audio Spectrum Visualizer
View the frequency spectrum of an audio file in real time while it plays, or directly from your microphone. Low frequencies appear on the left side of the graph and high frequencies on the right.
How It Works
The sound is broken down in real time into its constituent frequencies using an AnalyserNode from the Web Audio API, which performs a fast Fourier transform (FFT) on the audio signal. Each bar in the graph represents the intensity of a specific frequency band at a given moment: the bars on the left correspond to low frequencies, those on the right to high frequencies.
What is this type of visualization used for?
It lets you visually identify the dominant frequencies in a recording (a voice, a bass, a piercing high note), spot a hiss or background noise concentrated in a specific frequency range, or quickly check the overall balance of an audio mix before exporting it.
Why do I have to click play to see the file's spectrum?
The analysis is performed on the audio stream actually playing: without active playback, there is no signal to analyze. The spectrum updates automatically as soon as you start playback, and stops cleanly when you pause or the file ends.
What happens if I deny microphone access?
Microphone mode requires explicit permission from your browser. If you deny it or no microphone is available, a clear error message is shown and you can continue using the audio file mode normally.
100% local processing: spectrum analysis is done entirely in your browser via the Web Audio API. In microphone mode, the sound is never recorded or sent to a server — it is only analyzed live for display, then immediately discarded.