HOW RECORDERS WORK

THE RECORDER'S MOUTHPIECE

section view of a baroque recorder's windway & labium

The airstream coming out of the windway interacts with the air column in the instrument's bore and oscillates around the edge or labium, as shown in the pictures below. .

The interaction between the windway and the recorder's air column The airstream oscillating around the edge of the labium.
Photos : Univesity of Eindhoven (Netherlands)

THE RECORDER'S AIR COLUMN

The recorder's bore contains a column of air that vibrates lengthwise in the following manner when the instrument is blown into:
An antinode (A), which is a zone with maximum movement and minimum pressure, forms at each end and a node (N), a high pressure zone with no movement, forms in the middle.
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.

Click on each picture for more detailed explanations The note names are those of the alto or treble recorder.

low f

(Click on the picture for more details)

The air column can be shortened by opening holes, giving higher notes, since the vibrating length is shortened. If the holes were large enough, opening a hole would be equivalent to cutting the air column completely at that point, but the holes are too small for this, which is why we can use fork fingerings (also called cross fingerings) to play semitones in particular

low a

(Click on the picture for more details)

low b
(a fork fingering)

(Click on the picture for more details)

low d

(Click on the picture for more details)

We can thus play over more than an octave up to g (a fork fingering on baroque type recorders)

middle g
(a fork fingering)

(Click on the picture for more details)

Of course, we can also lengthen the air column again by closing the open holes.

To play higher notes we can force the air column to divide into two parts. On the recorder this is done by making the thumb hole leak. We now have two nodes and each vibrating segment is shorter. This enables us to use the same holes again for other notes.

middle a
(2^nd register)

(Click on the picture for more details)

By making two leaks (the thumb hole and one on the other side of the instrument), we can force the air column to divide into three parts, giving notes higher still, using the same holes once more. .

high e
(3^rd register)

(Click on the picture for more details)

By making three leaks (the thumb hole and two holes on the top of the instrument) we can force the air column to divide into four parts, giving even higher notes.

high g
(4^th register)

(Click on the picture for more details)

In this way we can play over a range of two octaves and a half (about 30 notes) using only 8 holes. However, the design of the instrument must be correct to enable this.

Preceding page

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