In his book "A Tramp Abroad", Mark Twain tells a story about a visit he made to Switzerland.

There he was, sitting quietly in a café, high in the Alps, when a band of strolling Yodelers -- clad in lederhosen -- stopped by his table ...and did their thing. Just minutes into the performance, Twain was so affected he felt compelled to toss the yodelers a franc a piece . . . to stop yodellling!

Despite Twain's efforts, yodelling endures - and not only in the Alps. In fact, it pops up - with shocking regularity - in the hippest of places.

Gwen Stefani yodelled in her hit single "Wind It Up".The Gorillaz yodel for the sheer joy of it on their newest CD. The Topp Twins, the yodeling lesbian sisters from New Zealand, are a hit with lovers of country and rock alike. And rap artist Mike Jones does it too.

Frank Faulk went in search of the yodel's timeless allure. This is his documentary "The Call of The Yodel."