Wind instrument, any of the musical instruments whose sound is produced by blowing air into a tube, causing a vibration within it. In woodwind instruments the vibration is made either by blowing across or into a specially shaped mouthpiece, as with the flute, piccolo, recorder, and flageolet, or by blowing against a single or double reed, as in the clarinet, saxophone, oboe, English horn, and bassoon. The pitch is altered by opening and closing holes set into the tube. In brass instruments the vibration is made by the player's lips on the mouthpiece. The bugle and various types of posthorn have a single, unbroken tube. The cornet, French horn, trumpet, and tuba have valves to vary the effective tube length and increase the range of notes; the trombone has a slide mechanism for the same purpose.