Wind instruments produce sound through vibrations created by a user's breath as it travels through the instruments' tubes. A person's breath causes the air molecules within a tube to collide and create sound waves. The notes and pitches produced by wind instruments are determined by how strongly a musician blows into the tubes, and each instrument's unique sound is determined by its characteristic shape.
Wind instruments must have an interior that is as smooth as possible in order to produce sound accurately. Depending on the specific wind instrument, a musician often relies on finger holes, valves or slides to manipulate the musical notes, controlling the direction of the sound waves and altering the speed of their vibrations as the air molecules pass through the instrument's tube.
Some wind instruments, such as trumpets and horns, have reeds at the mouth area that musicians maneuver with their lips to create different vibrations within the sounding tube. The mouthpieces of trumpet-type aerophones are part of a system of components within these wind instruments that work together to alter an instrument's unique tone. These accessories include the cup, throat and backbore, and their respective size and shape determine whether an instrument's tone is bright, deep or mellow.