I have never tried it, but I can see, especially on those busy trails where maybe you are trying to find solitude where there isn't actually any, it would make sense. Out in the actual wilderness, though, I can't see using one--you would miss a lot of natural sounds, I think. Right now the elk are starting to bugle. Would hate to miss hearing that!
I listen to music only in the car. I have this thing about wanting a quiet, peaceful house, but I love to blast rock n roll in the car! Since I don't drive much, it's a treat to get in the car and find some old favorite in the CD folder.
On a bike I think it would just be courting suicide, though, especially on the street.
There is a point of no return unremarked at the time in most lives. Graham Greene The Comedians
A clean house is a sign of a misspent life.