Take the sound into the frequency domain a frame at a time (a Short-Time Fourier Transform), edit the spectrum, and transform back — the analysis/resynthesis loop behind spectral effects. Freeze captures one frame's magnitudes and holds them forever, sustaining a sound with no loop point (the phase keeps advancing so it stays alive). Blur smears the spectrum across time; the band gate silences everything outside a frequency window; robotize flattens all phase so the sound re-periodicizes at the frame rate — a monotone robot. The FFT and the frame plumbing are unit-tested in Node; this page just edits the bins.
Bigger frames resolve pitch better and smear time more — the fundamental spectral trade-off.
play the source (a s d f …), start a drone, then hit freeze and sweep the controls