Mix a steady tone with a train of drum-like clicks and HPSS should pull them
apart: the sustained tone lands in the harmonic panel, the clicks in the
percussive panel. The three spectrograms below show the mixture and the two
separated halves. Technically: 1 s of 440 Hz sine + 10 broadband clicks →
stft(1024, 256) → magnitude → hpss(); the
horizontal 440 Hz line must land in the harmonic panel, the vertical click
stripes in the percussive panel. Badges mirror
examples/node/decompose-hpss.mjs: 440 Hz-bin dominance,
click-column dominance, margin=1 complementarity (H + P == S per bin),
masks summing to exactly 1, and the power=∞ strict 0/1 hard mask.