Overtone flute

An overtone flute is a type of a flute that is designed to play in the upper harmonics, typically well above the two or three harmonics that are the practical limit for most woodwind instruments.

An overtone flute has either no tone holes, or relatively few tone holes for a woodwind instrument. To make melodies, one plays it high into the overtone series. One series of harmonics is achieved by overblowing with the end of the tube open and another is achieved with the end closed; when the end of the flute is closed, the key drops by one octave and only the uneven harmonics can pop out. This means that overtone flutes without tone holes will produce mostly the notes present in the natural scale, whilst certain notes can be bent a bit by partially covering the end of the flute.