How Recorders Work - the Air Column: high g

PHILIPPE BOLTON, RECORDER MAKER

Medieval, pre-baroque, and baroque recorders

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THE RECORDER AIR COLUMN: high g

The following chart shows how the recorder's plays high notes.
Antinodes (A) are low pressure zones with high velocity or movement. Nodes (N), on the contrary are high pressure zones with no velocity or movement. If the bell is open there is always an antinode at each end.

This note belongs to the fourth register. The leaking thumb hole, combined with two other open holes in the correct places inhibits the nodes of the first three registers and thus causes the air column to divide into four parts.. There are four nodes here. Not only do the vibrations go up and down from the ends of the air column to the nodes, but also between the nodes, with maximum velocity at the antinodes.

The chart shows the position of the nodes and antinodes. There is one graph for velocity and one for pressure variations along the air column. The arrows show the direction of the vibrations. The recorder's bore profile, and the open (o), closed (x),and partially closed (ø) holes are shown underneath.

Recorder air column

= leaking thumbhole = closed hole

This chart is for a baroque alto or treble recorder.
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Philippe BOLTON,
le Grand Portail, F-84570 VILLES SUR AUZON, France
TEL +33 4 90 61 86 11 FAX +33 4 90 61 97 82