The Irish flute is a name for a wooden flute used in the playing of Irish traditional music. Sometimes the term is also used to distinguish diatonic, simple system flutes from 19th century flutes which played a diatonic scale by successively uncovering the toneholes but were made chromatic by the addition of metal keys. Some musicians consider the term "Irish flute" to be a misnomer, as the instrument is just a development of the older, simple system flutes, and is used in a wide variety of music, including Scottish music, Breton music, and others.
Irish flutes were originally old English simple system flutes that were discarded by concert musicians during the advent of the modern, Boehm system, Western concert flute in the late 1800s. These "obsolete" flutes were picked up at low cost by Irish traditional musicians. Today, Irish flutes are being made expressly for the playing of Irish traditional music by many makers. These modern Irish flutes often have few, if any keys, which is one difference between them and their predecessors, which had anywhere from 5-10 keys in addition to the standard six open holes. Some of the best known modern flute makers include Michael Grinter, Patrick Olwell, Sam Murray and Hammy Hamilton and Martin Doyle (flute maker). Terry McGee is also a well known maker of Irish flutes and his website (listed below) has a wealth of information.
Irish flutes are usually made out of wood, but are also occasionally made out of composite materials such as Delrin. Both materials have fairly similar musical characteristics, however, at least in comparison to metal flutes. Some makers also make more inexpensive practice flutes out of other materials, such as PVC or metal. Due to its wood headjoint, characteristic embouchure, the direct (keyless) fingering of notes in two major scales, and the characteristic manner of playing which is part of the Irish music tradition, the simple system flutes have a distinctly different sound than the Western concert flute. The tone of both instruments of course varies greatly with the player, but in general the simple system flutes have a bit of a darker, reedy tone and the direct fingering and style of playing gives the notes just a bit of portamento.
There are two main styles of Irish flute, the Pratten and the Rudall & Rose. The Pratten has wider bore dimensions and provides a louder sound, while the Rudall & Rose has a darker, pure tone and is slightly thinner than the Pratten style flute. Some flutes have an extra two holes on the end, which are meant to stabilize the tone and are not meant to be played.