Left ear bud produces a tinny/rattly sound.

My left ear bud started sounding tinny this morning, as in it is rattly and has a poorer sound quality than the right. How can I fix this?

crwdns2934089:0crwdne2934089:0 crwdns2934093:0crwdne2934093:0

crwdns2934109:0crwdne2934109:0

crwdns2889612:0crwdne2889612:0 0
crwdns2934285:0crwdne2934285:0