A slide whistle (variously known as a swanee whistle, piston flute or less commonly jazz flute) is a wind instrument consisting of a fipple like a recorder's and a tube with a piston in it. It thus has an air reed like some woodwinds, but varies the pitch with a slide. Because the air column is open at one end and closed at the other, it overblows the third harmonic.
The slide whistle is most commonly used as a sound effect (such as in the sound tracks of animated cartoons, to suggest something rapidly ascending or falling), but it is also possible to play melodies on the slide whistle.
The instrument became common in the 1920s when it was occasionally used in popular music and jazz as a special effect. Louis Armstrong switched over from his more usual cornet to the slide whistle for a chorus on a couple of recordings with King Oliver's band and his own Hot 5.
At that time, slide saxophones, with reeds rather than a fipple, were also built.
The slide whistle is today thought of primarily as a kind of "toy" instrument, but has been used by classicalcomposers, with Maurice Ravel possibly being the first, when he called for one in his ballet, L'enfant et les sortilèges.
