The hand flute, or handflute, is a sort of musical instrument made by the hands. It is also called a 'Hand ocarina' or 'Hand whistle'. To produce sound, one creates a type of chamber with their hands, which they blow into between an opening at the thumbs. There are two main techniques involving the shape of the hand chamber: the "cupped hand" technique and the "interlock" technique. 
The pitch depends on how the hands are held. If the space between the hands is made smaller or the opening made larger, the pitch becomes higher: the principles are the same with an ocarina or Helmholtz resonator; see vessel flute for details of the acoustics. The best hand flute players in the world have a range between 2.5 to 3 octaves.