The bone flute

[@MabInstruments]

This seems to be a fipple flute, but I'm not sure exactly how the sound hole is working. I've made fipple flutes before. Usually, the air from the bit you blow into flows over the sound hole. As I'm imagining the internal design of this flute, I see the air flowing under the sound hole instead. Can you show the internal arrangement (in a diagram perhaps) of how the air flows in relation to the sound hole, please?

[@jensbonde6524]

In this video from Vorland. In his video you can se it better. kzbin.info/www/bejne/hWmtqaaVqpuXaNk