Documents dating back to before 1000 BC describe a wind instrument whose reed vibrates back and forth across the frame that houses it. Nowadays, free-reed instruments inspire both scholarly study and musical innovation. James Cottingham , Acoustic of free-reed instruments, Physics Today, March 2011, Vol.63, pp. 44-48.
A free reed? What is it? More http://www.patmissin.com/history/whatis.html