Yiyin is one of the most commonly used decorative tones on bamboo flutes. Generally, there are two types: single and polyphonic. Appropriate use of appoggiance can enrich the expressive power of the music according to the needs of the content.

A small note added to the upper-left corner of a note is called an appoggi. Add two horizontal lines below the minor note and connect it to the primary note with an arc. Adding two or more small notes to the upper left corner of a note is called polyphonic appoggiance, and also connects them with the primary note with an arc.

When playing the appoggiator note:

   1. The time occupied by the appoggiance is extracted from the original sound, and the time of the original tempo cannot be increased.

   2. When playing a single appoggiance, the small note is spit out, and the original note does not need to be spit out. If the single appoggiance is on the strong beat, the note should be played stronger.

   3. When playing polyphonic appoggiance, the first small note should be spit out, and the other notes (including the original tone) should not be spit out, but should be played more coherently. Because a few small notes only take up a fraction of the duration of the original, the faster you play, the better. If the polyphonic appoggiator is on the strong beat, the native sound should be played stronger.