It is traditional in the Alps, i. e. Bavaria, Austria, Switzerland, Southern Tyrol for singing; as means of signalling and communication you also find it with the African Pygmees, Escimoes, in China, Thailand and Cambodja, Melanesia, Spain, Sweden, Poland, and Rumania.
Characteristics: meaningless sounds, rapid change between normal voice and falsetto, broad range of tones, great intervals.
Best known German yodeller: Franzl Lang; use in American country music: Jimmy Rodgers. World record for yodelling: Canadian Don Reynolds with 7h 29'.
In the German TV you may somtimes see a Japanese guy in Bavarian clothes yodelling Bavarian style. Funny to see, but really good performance.