PHILIPPE BOLTON, RECORDER MAKER
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 Version française Home page Recorders page |
THE RECORDER AIR COLUMN: middle a
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The following chart shows how the recorder's plays high notes. When a wave goes down the instrument from the windway end, a corresponding wave goes up the instrument from the other end. These meet at the node and bounce back in the opposite direction. When they reach their respective ends they bounce back once more, and this continues as long as the player keeps blowing. This note belongs to the second register. The leaking thumb hole inhibits node of the first register and thus causes the air column to divide into two parts, giving a note an octave above the first register. There are two 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. Opening a hole could amount to cutting the air column at that point, but on recorders the holes are not big enough, so the air pressure and velocity diminish gradually further down. This makes cross or fork fingerings possible. |
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 = leaking thumbhole  = closed hole
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| This chart is for a baroque alto or treble recorder. |
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Philippe BOLTON, |
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