Swiss and Tyrolean mountaineers have developed the yodel as a means of vocal communication over great distances. A melody or musical phrase is sung with interchange between the ordinary and falsetto voice. The call is inarticulate, so communication is by means of sound rather than language. The word has also been used to mean any musical cry; it was used by the novelist du Maurier in 1894 to refer to the call of the British milkman. Coincidentally, this occurs in his best-selling work, Trilby, a book which should be required reading for all singers.
