What we are actually visualizing
The Web Audio API exposes sound as numeric arrays. With an AnalyserNode, we can inspect frequency energy per frame and map it to geometry, color and motion.
Why FFT changes everything
FFT converts time-domain waveforms into frequency bins. That means bass, mids and highs become independently controllable signals for visual systems.
Initialization Pattern
audio_engine.js
const ctx = new AudioContext();
const analyser = ctx.createAnalyser();
analyser.fftSize = 512;
const data = new Uint8Array(analyser.frequencyBinCount);
function tick(){
requestAnimationFrame(tick);
analyser.getByteFrequencyData(data);
draw(data);
}[ REAL-TIME_SIMULATOR ]
> Awaiting user gesture...
From signal to meaning
A real-time visualizer is both engineering and composition. With this base, you can move to shaders, particles, 3D fields and full immersive installations.
