Conductive hearing loss is a form of hearing impairment where the transmission of sound from the environment to the inner ear is impaired, usually from an abnormality of the external auditory canal or middle ear. This form of hearing loss can be temporary or permanent. Untreated chronic ear infections can lead to conductive hearing loss. If fluid is filling the middle ear, hearing loss can be treated by draining the middle ear and inserting a tympanostomy tube. The other form of hearing loss is sensorineural hearing loss, hearing loss due to abnormalities of the inner ear or the auditory division of the eighth cranial nerve. Historically, this condition can occur at all ages and is usually permanent.
A hearing test should be performed for children who have frequent ear infections, hearing loss that lasts more than six weeks, or fluid in the middle ear for more than three months. There are a wide range of medical devices now available to test a child’s hearing, Eustachian tube function, and flexibility of the eardrum. They include the otoscopy, tympanometer, and audiometer.
Children and adults can incur temporary hearing loss for other reasons than chronic middle ear infection and Eustachian tube dysfunction. They include:
- Cerumen impaction (compressed earwax).
- Otitis externa – Inflammation of the external auditory canal, also called “swimmer’s ear.”
- Cholesteatoma – A mass of horn-shaped squamous cell epithelium and cholesterol in the middle ear, usually resulting from chronic otitis media.
- Otosclerosis – This is a disease of the otic capsule (bony labyrinth) in the ear, which is more prevalent in adults and characterized by formation of soft, vascular bone leading to progressive conductive hearing loss. It occurs due to fixation of the stapes (bones in the ear). Sensorineural hearing loss may result because of involvement of the cochlear duct.
- Trauma – A trauma to the ear or head may cause temporary or permanent hearing loss.