the physics of wind instruments is based on the concept of standing waves. when the player blows into the mouthpiece, the column of air inside the instrument vibrates, and standing waves are produced. although the acoustics of wind instruments is complicated, a simple description in terms of open and closed tubes can help in understanding the physical phenomena related to these instruments. for example, a flute can be described as an open-open pipe because a flutist covers the mouthpiece of the flute only partially. meanwhile, a clarinet can be described as an open-closed pipe because the mouthpiece of the clarinet is almost completely closed by the reed.