Duct flutes

• Vessel flutes with duct [421.221.4]
• Tubular flutes with duct [421.221.1]

These flutes are played by blowing into a duct that channels the air to the edge of a hole in the mouthpiece. A well-known example is the recorder.

They belong to category 421.2 of the Hornbostel-Sachs classification.

Explanation and examples

With no duct

We know that we can make a hollow nut, once pierced, to whistle. This is achieved by blowing a thin stream of air at a very precise angle onto a very precise spot on the edge of the hole. Viewed in cross-section and in profile, it can be schematised as follows: a window (1) opened between the inside and the outside, the edge of which is a bevel (2).

Unfortunately, it takes a bit of practice to manage to produce a sound.

With duct

To play more easily, we can add a small tube (made of reed, for example), carefully glued in place, which will direct the air at the right angle to the best spot.

This small instrument now features the main components of a flute with a bore: a window (1) flanked on either side by the bevel (2) and the duct (3).

The block

Whilst a duct flute mouthpiece is easier to play, it is more difficult to make. A well-made duct requires precise adjustment to ensure that the air stream produced is sufficiently narrow and directed to the correct position. This generally requires a precision of around a quarter of a millimetre; this is why one of the duct’s walls might be a movable part, which is easier to adjust: the block (4).

Here is the mouthpiece of a recorder…

… and that of a Native American flute…

• 1 : Window.
• 2 : Bevel.
• 3 : Air duct.
• 4 : Block.