The sound production of the saxophone begins with the mouthpiece and reed. Through
combined lip pressure underneath the reed and air pressure into the mouthpiece, the reed vibrates
rapidly over an opening into the mouthpiece, closing entirely over the mouthpiece about 50% of
the time, being completely about open 25% of the time, and being in motion about 25% of the
time. This process displaces air inside the mouthpiece and thus causes a vibration of the air
column throughout the instrument, with the frequency determined by the length of the tube.