Some years ago I had a copy of the shown cd, Blue Yodelers 1928-1936 (Retrieval, RTR 79020), containing tracks featuring Jimmie Rodgers, Emmett Miller and Roy Evans with ccompaniment by various jazzmusicians of the period, reliving a mostly forgotten chapter of early jazz with great audio examples of recordings made by the mentioned artists. The Jimmie Rodgers recordings have a couple of examples of his most notable musical innovation, a series of songs he called Blue Yodels.
In his short career Rodgers recorded thirteen Blue Yodels. Blue Yodels were blues songs in style, sound, and lyrics. They generally told of serious trouble, sometimes of violence between men and women, and they rarely had nostalgic or happy endings. Yodeling came from various sources, perhaps from cowboy songs or from the songs of travelers in the Swiss Alps. Rodgers was not the first musician to sing “Yo de lay hee-ho” between verses of his songs, but he made it such a trademark that some people assume country music has always included yodeling.
In 1929 Columbia made a movie short,"The Singing Brakeman" featuring Jimmie Rodgers performing some of his songs. I insert a couple of fragments from this movie short uploaded at YouTube - the first, "T For Texas" also known as Blue Yodel No 1