What bit is used for the inner hole of suona rod?

Suona is also called trumpet, small suona is called hand flute, and big suona is also called sea flute. Suona, there are eight holes (the first seven and the last one) in the wooden cone. The upper end of the tube is equipped with a thin copper tube, which is sheathed with a double-spring reed whistle, and the upper end of the wooden tube is equipped with a copper bowl-shaped speaker. Although the suona has eight holes, the sound of the seventh hole is the same as that of the drum, and the sound of the eighth hole is the same as that of the first hole. Commonly known as "horn". Folk musical instruments are widely circulated in all parts of China. The pronunciation is loud and clear. In the past, it was mostly used to accompany folk song blowing parties, yangko parties, drum music classes and local folk operas. Through continuous development, it has enriched the playing skills and improved the expressive force, and has become a unique solo instrument, which is used for national band ensemble or opera, song and dance accompaniment.