Types of Hearing Loss
Hearing loss is categorized into three basic types. The type of hearing loss is determined by which part of the auditory system is damaged.
Conductive hearing loss occurs as a result of a problem in the outer or middle ear. Common examples of conductive hearing loss include ear canal blockage, ear drum perforation, ear infection, fluid accumulation in the middle ear space, and damage to the tiny bones of the middle ear. Any of these conditions can be the result of blunt or blast combat trauma.
Conductive hearing loss is usually perceived as a reduction in sound level or an inability to hear faint sounds. Depending on the cause of the conductive loss, these conditions can resolve spontaneously with medical management, or if they don’t resolve, they can often be corrected surgically.
Sensorineural hearing loss often results from damage to the cilia, or hair cells, in the inner ear or to the nerve pathways from the inner ear to the brain. This type of hearing loss can also be the result of damaged anatomy due to trauma.
Sensorineural hearing loss is most commonly caused by exposure to loud noises or age-related changes to the nerves and sensory cells of the inner ear. Metabolic, cardiovascular, congenital, or inflammatory disorders can also contribute to or cause sensorineural hearing loss. This type of hearing loss reduces the ability to hear faint sounds. Even when speech is loud enough to be heard, it may sound muffled or unclear. Sensorineural hearing loss is the most common type of permanent hearing loss.
Mixed hearing loss is a combination of conductive and sensorineural hearing loss. There may be damage to the outer or middle ear, as well as in the inner ear or along the auditory nerve. Mixed hearing loss can be caused by a head injury, chronic infection, or an inherited disorder.
Hearing loss is also classified by degree or severity. These include:
- Mild hearing loss: One-to-one conversations can be heard, but it’s difficult to catch every word if there’s background noise
- Moderate hearing loss: You may need to ask people to repeat themselves during one-to-one and telephone conversations
- Severe hearing loss: Following a conversation is difficult without a hearing aid, and
- Profound hearing loss: You cannot hear other people speaking, even if they speak loudly or if hearing aids are used. Cochlear implants can be considered for these profound but rare situations in order for you to process speech.