Liam O'Brien does not have cancer, but he does suffer from hyperacusis, a type of hearing loss. This is because he was diagnosed with acoustic neuroma, a type of brain tumor, when he was 28 years old. Acoustic neuromas are tumors that develop on the auditory nerve or in the area of the ear where it connects to the brain. They can be found anywhere along the pathway that sound travels from the outer ear to the brain. Although most people do not know they have an acoustic neuroma, about two-thirds of those who do are already experiencing some degree of hearing loss. The other one-third have no symptoms at all. Acoustic neuromas are usually identified by pure-tone audiograms (tests that measure how loud sounds need to be for you to detect them) and/or speech recognition scores. People with acoustic neuromas may experience dizziness, facial pain or pressure, memory problems, vision changes, and trouble walking. The medical term for someone who suffers from acoustic neuroma is "neurotologist". Because of its relationship to the auditory nerve, an acoustic neuroma must be removed completely if it is to be cured. Hearing can then be restored by means of a prosthesis known as a cochlear implant.