I loved the title of this article, and for the most part it delivered as promised. I don't know about the John Cage part...
But there are a few videos to show what this creative and unique group has done with yodeling to create a new sound.
Here's an excerpt from the article:
The foursome, created earlier in 2010 in its present form, played an astonishing repertoire of music that defies classification, starting with the odd variety of instruments: bass, guitar, clarinet and yodeller. Nadja Raess is a yodeller who is also a classically trained singer from the Zurich Conservatory, and while she sometimes performs and sings traditional yodel music, this was billed as an evening of classic wordless yodels with modern variations for yodel as an instrument, her specialty.
Equally impressive was the variety of music, ranging from a handful of traditional yodel songs, which some in the audience were clearly expecting, to dissonant jazzy pieces as well as melodic, well-crafted quartet music closer to Brahms' lullabies than mountain hullabaloo stuff.