[Spoken]
Jimmie Rodgers earned the title of "America's Blue Yodeler" by composing and performing a series of twelve "Blue Yodels"

Jimmie by no means invented the yodel, but provided the yodel a unique interpretation by combining it with the blues. Jimmie made the yodel work for him. His yodel could display pain, loneliness, or even a happy frame of mind

Somebody said that Jimmie often inserted the yodel because he ran out of lyric, but I prefer to think that Jimmie Rodger's yodel more often than not displayed his real feelings better than any lyric could have