The eardrum converts sound waves into nerve impulses that are sent to the brain, and protects the middle ear from bacteria, moisture and other foreign objects. A perforation can disrupt both important functions. When an eardrum is ruptured it can allow bacteria to enter the ear and cause an ear infection (otitis media). A rupture or perforation can also create a hole; just like a drumhead is worse at carrying sound with a hole in it, your tympanic membrane is too. This is the reason a rupture can contribute to a loss of hearing.