falsetto
A vocal technique producing pitches above the normal range by using a lighter mechanism.
In Depth
Falsetto is a vocal register above the normal (modal) voice, produced when the vocal cords thin and elongate, vibrating only along their edges rather than their full mass. The resulting tone is lighter, breathier, and less powerful than the full voice, though some singers develop a remarkably strong falsetto.
In popular music, falsetto has been used by artists from The Bee Gees and Prince to Radiohead's Thom Yorke and Jeff Buckley. In classical music, the countertenor voice uses a refined form of falsetto to sing alto and soprano repertoire originally written for castrati. The technique requires careful training to produce a consistent, controlled sound.
The Bee Gees originally sang in their normal voices. They switched to falsetto for Saturday Night Fever and it became one of the best-selling soundtracks in history.