The most important piece of the clarinet instrument is the clarinet mouthpiece. If an analogy is to be drawn, it can be said that it is the heart of the clarinet, because no matter how good the model and the brand of the clarinet, if the mouthpiece used is not made good enough or not prepared properly for the clarinet, this constitutes a major problem for the performer. Another name of the mouthpiece is '' bek''. Clarinet mouthpieces show differences among themselves both in types of instrument and the pieces to be played. The varieties of the mouthpieces used in classical music, jazz music, and Turkish music are distinguished among themselves. The clarinet mouthpieces we use today are two types as handmade and fabricated. Some fluctuations and changes can be made on the clarinet mouthpieces made in the factories; the aim of this is to make the clarinet in a form that can respond to the shape and the technique of the clarinet player's blowing better. The most important feature that should exist in the mouthpieces is the materials used and the tunning are well.
Keywords: Clarinet, mouthpiece, performer, turkish music.