Regal

One cycle of the last key's reed, slowed down a few hundred times, side on, its height drawn ten times its length's scale: the curved brass tongue rolls onto the shallot's flat face from its root to its tip, shutting the gap and the flow, and springs back. Below, the same cycle as traces: the flow stops dead each time the tongue lands, and the air in the shallot, still moving, pulls its pressure far below the wind's.

Above: the shallot and its resonator, to scale. Below: what the tongue blows into, the tube's input impedance |Z| (log) from the note to its 16th harmonic, ticks at the harmonics. The resonator is a small fraction of a pipe's length, so its first peak lies above the note: the tongue sets the pitch, and the peaks lift the harmonics near them, the regal's nasal formants.

Two wedge bellows, weighted. One sinks as the reeds draw on it while the calcant raises the other; when the first is down the other takes over, its board settling onto the wind with a little shake. A sinking bellows' wind rises a few per cent (its weight's lever arm grows), and a chord coming in gives a dip as the board gathers speed. The tremulant's vent pulses it.

A beating reed shuts the flow off once a cycle, so every harmonic is there, falling slowly; the resonator's peaks lift the ones near them.

A regal speaks almost at once, the harmonics together. Watch them waver with the tremulant, and dip as a big chord sags the wind.