The mouthpiece and the reed are the most important parts of the clarinet and the saxophone. To assemble, the reed is bound to the mouthpiece with a metal or leather ligature (and sometimes with a string, which may be woven). To test reeds quickly, the player can fix the reed to the mouthpiece using the thumb, which works as a ligature as a few notes are played.
When playing, air streams into the opening between the reed and mouthpiece. The change in air pressure between the reed and the mouthpiece gives the reed an impulse which causes it to bend towards the mouthpiece window. As the reed is elastic, it begins to swing. Continuous air flow causes the reed to vibrate. The reed’s vibration then causes the air column to pulse inside the bore of the instrument between the mouthpiece and open tone holes. This is how the tone is created. The tone quality and response are dependent on several different factors; the greatest being the quality of the mouthpiece and reed. It is essential that the reed fits the mouthpiece properly, in other words: the correct cut and strength of reed should properly match the specific dimensions of the mouthpiece facing.
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