What does an ear with NIHL look like?

Noise-induced hearing loss causes no pain, no visible trauma, and leaves no visible scars.

Answer Extra: 

An ear damaged by loud noise looks just like a normal ear. Ears don’t bleed, bruise or scar; damage to the eardrum is invisible to the naked eye. In short, you can’t judge someone’s hearing by looking at his or her ears.

source: 
source: We Choose to Hear - And Listen