Here is a blaclaw tribal shaman (around the Alabama-Florida area) playing a nasal flute known as a "wils" (from the prepulse word Whistle) playing the flute to dispel bad spirits from an area. It is common to do this in hatcheries and with the sick to try and get the evil spirits hurting those things away. Alternatively the blaclaw shamans of some tribes instead use a single pluck stringed instrument known as a "Banje", a misnamed instrument being related to the prepulse banjo, though it doesn't quite sounds like a banjo.

Drekir can exhale through their mouths, but lacking lips they have a hard time controlling that breath to make a mouth blown flute ergonomic. Nasal flutes are a work around that is common amongst most cultures that make flutes for their own variety of reasons. Overtone flutes are more or less large whistles mechanically speaking and are more of a rhythmic or timbral instrument as they can only play the pitches of the overtone scale relative to their base pitch. Blocking the end hole as this drek is about to do can add a harmonics tone to the flute. In this case the flute is more of a rhythmic instrument.
Flutes like this one are made out of regional rivercane, bamboo that is pretty easy to turn into a flute though they can also be made of animal bones or entirely carved of wood.