An AnalyserNode is a built‑in Web Audio API node that captures real‑time audio data for frequency and time‑domain analysis. It sits in your audio graph and provides two key views: frequency data (via FFT) showing the amplitude of each frequency bin, and time‑domain data showing the raw waveform samples. This powers visualizations, audio meters, and diagnostic tools without altering the audio signal.

FFT size is a trade‑off between frequency resolution and time resolution. A larger FFT (e.g. 4096 or 8192) gives finer frequency detail—great for spotting specific harmonics—but responds more slowly to transients. A smaller FFT (e.g. 256 or 512) updates faster, better for percussive sounds. The default 2048 is a balanced starting point for most use cases.

The X‑axis represents frequency (low bass on the left, high treble on the right, up to half the sample rate—the Nyquist frequency). The Y‑axis shows amplitude in decibels (dB). Taller bars or higher curves mean louder energy at that frequency. A pure tone will show as a single sharp peak; music or noise shows a complex, ever‑changing landscape of peaks and valleys.

The waveform (time domain) shows air pressure over time—the raw shape of the sound wave. It's great for spotting clipping, asymmetrical waves, or silence. The spectrum (frequency domain) decomposes that wave into its constituent frequencies, revealing pitch, timbre, and harmonics. They are two complementary views of the same signal, connected by the Fourier transform.

Microphone access requires HTTPS (or localhost) and explicit user permission. On iOS/Safari, you may need to enable microphone access in Settings. Also check that no other app is using the mic. Click the microphone button and look for the browser permission prompt—you must allow access. If denied, you can reset permissions in your browser's site settings.

The smoothingTimeConstant (0–1) controls how much the frequency data is averaged over time. A value of 0 means no smoothing—the visualization reacts instantly to every change (appearing jittery). A value near 1 applies heavy smoothing, creating a slower, more stable display. The default 0.8 works well for most musical material; lower values are useful for analyzing fast transients.

This tool relies on the browser's native audio decoder, which typically supports MP3, WAV, OGG/Vorbis, FLAC, AAC, M4A, and WebM. Uncompressed WAV files work universally. If a file doesn't play, try converting it to a standard format. Maximum file size depends on browser memory; very large files (over ~200 MB) may be slow to decode.

Yes—the dominant frequency display shows the loudest detected pitch in real time. For tuning, use the microphone or test tone mode. A pure sine wave at 440 Hz should show a dominant frequency very close to 440 Hz. Keep in mind that background noise and harmonics can affect accuracy; for precise tuning, a dedicated tuner is recommended, but this tool provides a solid reference.