Yes, rock music can be appropriate for babies to listen to; if you play it at a lower volume to prevent startling the baby. The best thing about babies; they can listen to any music just depends on how you play it, because it help to soothe them like it does for adults.
Rock music like every other style of music if played to a baby, chances are he or she may grow up to love and imbibe it. All babies are born with the potential to become musical, and they often react to songs with enthusiasm. Infants' hearing is well developed soon after birth, so they can respond to music very early on.