is a significant or total loss in hearing of a person, affecting both ears or only one. Typically, deafness is categorized into two groups depending on the anatomical location of the hearing loss: conductive hearing loss is when the external and/or middle ear components are affected, possibly due to an obstacle located in the external ear canal, or a condition affecting the ear drum
, the membrane that transmits vibrations to the inner ear. Sensorineural hearing loss is when the inner ear is affected, which is the area responsible for transforming the vibrations received into neural messages that can be interpreted by the brain. In these cases the condition can be directly affecting the inner ear, such as with certain infections like mumps
, or can be due to ototoxic drugs, or can be due to neural damage such as that observed in multiple sclerosis
, a tumor
on the nerve. The distinction between these two types of deafness is made using tests with a tuning fork that is struck to vibrate. A brain scan is also commonly required to identify the cause for the impairment and design a treatment method.