Chladni Choir

Drag across the steel plate to sweep the driving tone — the sand migrates onto the silent nodal lines, and the pattern you see is the chord you hear.

Interval: … — the two loudest plate modes, named as what you hear.

Drag horizontally to raise the frequency (finer patterns, higher modes); drag up for more excitation (a wider resonance rings more modes into a chord). Left idle, a seeded sweep keeps the plate singing on its own.