Polyphonic Embouchure (finger-embouchure)
Recent "waterflute" installations as fountains in public parks allow for a kind of reverse-embouchure. Whereas traditional instruments are supplied with compressible fluid (air) from the mouth of a player, the new waterflutes supply incompressible fluid (water) to the player, and sound is made when the player resists this supply of fluid. Water flows out through mouths of the instrument and the player blocks this flow of water to make sound. As a result, the player can put one finger in each of several of the instrument's mouths, to play a chord, while independently controlling the embouchure of the sound made at each mouth. Additionally, the player's own mouth is free to sing along with the instrument, while the player can independently affect the sound of each of several different musical parts with this "finger embouchure". Such instruments are referred to as hydraulophones. Finger-embouchure can be used to make a wide variety of sounds, ranging from a buzzing sound like that made by a defective faucet, to a very pure tone similar to the sound made by a glass harmonica. Finger embouchure can also be used to affect the intonation or temperament. For example, a skilled hydraulist can use finger-embouchure to remain in a just intonation while changing keys, or to fluidly vary the intonation of a chord while it is sounding.
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