This sentence uses an exaggerated method to say that a bird can fly up to eight miles high and fall from the top to express that the folk song was quickly abandoned and turned to rock and roll.
This sentence exaggerates that birds can fly up to eight miles and fall from the ground, expressing that ballads are quickly abandoned and like rock and roll.
This sentence uses exaggeration to say that birds can fly eight miles high and fall from the sky, which shows that folk songs are quickly abandoned and they like rock and roll instead.