Hornbostel - Sachs
Reedpipes with free reeds
The air itself is the vibrator in the primary sense. The standing waves are significantly confined within the instrument itself. The column of air is made to vibrate by the intermittent access of an air stream produced by means of a lamella. The reed vibrates through [at] a closely fitted frame in the wall of a tube. The instrument has two pipes with reeds. It is tuned by altering the lengths of the air columns. There must be fingerholes in the pipes, otherwise the instrument belongs to the free reeds.
Double reedpipes with free reeds