Willow flute

The willow flute, also known as sallow flute, is a Nordic folk flute, or whistle, consisting of a simple tube with a transverse fipple mouthpiece and no finger holes. The mouthpiece is typically constructed by inserting a grooved plug into one end of the tube, and cutting an edged opening in the tube a short distance away from the plug. Similar, however not the same instruments were made by peasants in Poland, usually using a different method described in sources as "kręcenie", "ukręcanie", "ulinianie". Such instruments are mentioned in folk poems or songs. The willow flute is a type of overtone flute. It is played by varying the force of the air blown into the mouthpiece, with the end of the tube being covered by the finger or left open. The tones produced are based on the harmonic series. Playing the instrument with the end of the tube covered produces one fundamental and its overtones, playing it with the end of the tube left open produces another fundamental and series of overtones. Willow flutes cannot be tuned to an equal tempered scale.