I pulled out the soundtrack to 'O Brother Where Art Thou?' over the weekend.  There's nothing quite like Americana.  True American root music.  Some call this style of music the 'high lonesome sound'. It's definitely a true art form born in the 'Deep South' and commonly known as bluegrass.  There's something about the musicians and the singers who can create this 'keening' effect.

 

The movie by the way is great too.  Check out the Soggy Bottom Boys on 'Man Of Constant Sorrow':