Listening to the wonderful Harmonic Overtones CDs that I reviewed last month, I heard something different. And now I have a theory.
If you listen to live or recorded throat-singing of the very deep kind that the Tibetan monks and some Mongolians do, you may notice that didgeridu playing sounds much like it.
Years ago I attended a workshop on making didgeridus and playing them. We each brought a length of PVC pipe about 3 inches in diameter and 4 or 5 feet long. At the workshop we sanded the ends till they were very smooth. Then we decorated the outside of the pipe with acrylic paint.
The result was an inexpensive, lightweight and virtually indestructible didgeridu that made a pretty good sound---if you knew how! The workshop leader could play but was not very articulate about how to do it. (He was a volunteer, teaching for fun.)
I'm not sure anyone had taught him. I think maybe he had taught himself intuitively by listening to recordings or other didgeridu players. I have since listened to both recordings and live didgeridu players and still could not figure out what they were doing.
I now suspect that real didgeridu players are actually doing a form of throat-singing (or multinote toning) into the didge, which then amplifies the growling sound and the overtones and undertones.
Most people do not talk about the undertones. Those are not as impressive as overtones and do not carry as far, I think. But they are important in the style of throat-singing that Tibetan monks do, and they may be the most important part of the didgeridu sound for healing.
If you experiment with this sound-healing method, please leave a comment, telling what you did. I would love to know how it worked out for you.