The pan flutes (also known as panpipes) are a group of musical instruments based on the principle of the closed tube, consisting of multiple pipes of gradually increasing length (and occasionally girth). Multiple varieties of panflutes have long been popular as folk instruments. The pipes are typically made from bamboo, giant cane, or local reeds. Other materials include wood, plastic, metal and ivory.

https://en.wikipedia.org/wiki/Pan_flute