There are many ways to produce vocal overtones. It depends by the structure of our vocal tract - tongue, cavities, ... - and our sensitiveness. We could explain our technique here.
"Dear Jan,
I received just today the message that you have died on 22. April 2022 after a short, serious illness.
So on this way a big thank you for our meetings in real life in Prague, Dresden,…"
Die CDSCHWINGEN DES LICHTSist ein Hinweisauf die formlose Stille.Über einem Grundtonschwingen die Obertöne.Nach dem Obertongesangerklingt die Stille.________...