Musical instrument classification experts divide the woodwind family of instruments into two types: reed instruments and flutes. While reed instruments produce their sound by forcing air past a reed or reeds, flutes rely on splitting a focused stream of air through a tube of variable lengths.
As mentioned above, the reed instrument family is divided into two subfamilies: single reed and double reed. Single reed instruments, like the saxophone and clarinet, produce sound by forcing air past a reed fixed to a mouthpiece by a ligature. Double reed instruments, like the oboe and bassoon, use precision-cut reeds fixed to one another. Air is forced between the reeds to create vibrations that interact with the length of the tube.
Flutes are also divided into two types: open flutes and closed flutes. With open flutes, such as the transverse flute and the ocarina, the player directs air immediately across a sharp edge, which splits the sound. In closed flutes, such as organ pipes and the recorder, the player blows air directly into the instrument, and that air is divided across a sharp edge farther down the tube.
The term wind instrument defines a category of music instrument that includes all instruments whose sound is created by air that has been directed into the instrument by the player. Within the wind instrument category, there are valved brass instruments, like the trumpet, sliding brass instruments, like the trombone, single-reed instruments, like the clarinet, double-reed instruments, like the oboe, open flutes and closed flutes, among others.
Wind instruments all feature a resonator, or a tube, that allows air to vibrate in accordance with the length of the tube. In order to change notes, players can make modifications to the flow of air, or change the length of the tube using keys or a slide. Some instruments, such as organ pipes and the pan flute, require that air be directed into one or more of several tubes of varying length and circumference.