For those like me who knothing about the instrument- There is a small hollowed out reservoir in which to blow.
Adding a bit to Jack Campin, tuning- "It has seven tones per octave, with intervals similar to that of the Western diatonic natural A-minor scale: A, B, C, D. E, F and G. A khaen can be made in a particular key but can't be tuned after the reed is set and the pipes are cut. If the khaen is played along with other instruments the others have to tune to the khaen."
Wikipedia. This applies to the Laotian instrument.

A better article on the khene here: V. Phraxayavong, "Lao National Musical Instrument and its Role in Lao Culture."
Khene