William Tell... was he the first yodeller?

Had a long day at work, so nothing cerebral here...

Here's a "knock, knock" joke that is supposedly a classic:
Knock, knock.
Who's there?
Little old lady.
Little old lady who?
Hey, I didn't know you could yodel!

Of course, everyone knows that yodelling started in the Alps. But Swiss or Austrian? The debate between these two countries went to and fro, much like a cuckoo clock's refrain, until a Swiss chap claimed that the legendary Swiss hero William Tell started it. This is what supposedly happened:

William Tell was still an energetic (and virile) handsome young man, traipsing the Alps often. One day, he spent the night in an Alpine lodge perched on a mountain top. The innkeeper's wife and three daughters were, well, comely.

That night, young William wasted no time as soon as the innkeeper fell asleep.

The next morning, he was well on his way and had already reached another mountain top, but within view of the lodge and within the valley's echo range, when he heard the innkeeper's angry voice berating him, clearly repeated by the echos across the valley: "You young rascal, how dare you seduce my three daughters!"

Cocky young William, from his safe distance, shouted back: "Haha, so I did". And the echoes went: Haha, so I did, haha, so I did...

William, after drawing a deep breath, next cried out: "And your old lady too!" which then echoed on and on for some time, enraging the livid old man even more.

And that was how yodelling started. If you believe all this, start yodelling away!