Hearing loss

External sounds reach the inner ear of a person in two ways. One is the air conduction pathway through the external ear canal, tympanic membrane, ossicular chain, and vestibular window, and the other is the bone conduction pathway that directly oscillates the external lymph by movement and compression of the skull. When sound passes into the inner ear, hair cells on the basement membrane of the cochlea undergo shear motion to generate action potentials, and electrical signals are transmitted to the brain along with nerves to produce hearing. If lesions occur in any of the above pathways, hearing will be affected.