An acquired ability to decipher the lyrics of Metal singers without any trouble at all. Some Metalheads never acquire this ability, having to either resort to searching up the lyrics or making up their own. If you ask what the lyrics to a song are near a person with Metal Ear, you'll likely be regarded with disgust and maybe an exasperated answer.
Guy: Why are you even listening to this crap? I can't make out a word of it.
Metalhead: That's because you never listen to it, and you obviously don't have the Metal Ear.
Guy: You're lying, I bet you don't even know what they're saying.
Metalhead: Get out of my car. Now.