Most flutes have 16 key openings to cover an equal-tempered octave. Many modern flutes can reach a range of three octaves with anywhere from 16 to 20 openings to play.
The flute, which on average is 66 centimeters long, produces sound when the musician blows air into the sharp edge. A particular note sounds when a key is pressed or a multiple number of the key holes is depressed. The sound is produced by the air enclosed in the tube of the flute that causes vibrations. Most flutes are side-blown and the musician uses all 10 fingers to depress the keys or hole openings.