Mong flute or Sao

Sao is usually used to designate a vertical bamboo flute pierced with finger holes. However, this term is often used by ethnic minorities to describe several woodwind instruments that are quite different in structure (single or double flutes, with or without a reed, with or without finger-holes, etc.) and in how to hold them. 

 The H’mong sao is a single flute with a reed and a colorful timbre. The H’mong call it tra pun tu. The sounds produced are harsh and sweet like whispers. Since it has been played on stage, the H’mong flute has captured the hearts of many audiences. It is being constantly improved to expand its sound capabilities. 

The H’mong flute accompanies young H’mong men at work and in love. For them, the flute is an effective way to reach a girl’s heart.

Source: Vietnam Tourism