Not entirely true. People in Indiana -say- that hoosier is a mystery word; it just means "a person from Indiana" and no one knows why. However, anyone who's studied Midwest dialects can tell you "hoosier" is a synonym of "hick" (and still a commonly used pejorative in precisely this sense in the ...
Yeah, it's probably coming from the powerlines. Most of the big honkers like that are pretty noisy.