If my old memory banks are functioning I believe that during a Grand European tour in 1967 I heard that yodelling was originally invented as an alpine communication system by the Swiss. High pitched sounds would carry better and since words would get lost a system of coded syllables was devised. I also seem to remember hearing that the local yodelling competition (performed by local yodels?) was divided into classical and free-style sections.
All of the above may or may not be true. Confirmations anyone.