Yodeling started out as a means of communications between next-door neighbors. But they were one peak instead of one door apart. Mountain peak that is.
Scenario: the Austrian Alps. It didn't need words. Just a loud sound and a strong voice. And whoever lives up there, where the air is almost unpolluted, does develop an enduring voice rather naturally!
Actually yodeling was originally called "Juchizn," an array of short yells which had different meanings, like "it's dinner time" or "it's a boy." Yodeling turned out to be so much fun that it quickly turned into an art form and it expanded into the Swiss and Bavarian Alps.
i lee o lady