The pan flute or pan pipe ( also known as panflute or panpipes ) is an old musical instrument that has five or more pipes of gradually increasing length ( and , at times , girth ) . The pan flute or pan pipe ( also known as panflute or panpipes ) is an ancient musical instrument based on the principle of the Closed tube , consisting usually of five or more pipes of gradually increasing length ( and , at times , girth ) .