The three types
Hearing depends on a chain: sound is collected by the outer ear, converted to mechanical motion by the eardrum and the three middle ear bones, then converted to nerve signals by the cochlea and carried to the brain. Hearing loss is classified by where along that chain the problem sits, because the location determines what can be done about it.
Conductive hearing loss arises in the outer or middle ear — anything that blocks sound from reaching the inner ear efficiently. Causes include wax, fluid behind the eardrum, a perforated eardrum, cholesteatoma, and fixation or erosion of the middle ear bones. Conductive loss is often correctable, either surgically or with a device that bypasses the blockage.
Sensorineural hearing loss arises in the cochlea or the hearing nerve. This is the most common permanent form, and includes age-related loss, noise-induced loss, genetic causes, and loss from certain medications or infections. The underlying damage is generally not reversible, but the hearing itself can often be rehabilitated very effectively.
Mixed hearing loss is a combination of both.
When to seek specialist evaluation
Some presentations warrant more than a routine hearing test:
- Sudden hearing loss in one ear, developing over hours or days — this is urgent
- Asymmetric hearing loss, where one ear is clearly and measurably worse
- Hearing loss with other neurologic symptoms — facial weakness or numbness, significant imbalance, or persistent one-sided tinnitus
- Hearing loss with drainage from the ear, or with a history of chronic ear infections or ear surgery
- Poor speech understanding despite hearing aids, which may indicate candidacy for an implantable device
- Hearing loss in a child, where early identification meaningfully affects speech and language development
Evaluation
A complete evaluation typically includes a history focused on the timing and pattern of the loss, an examination of the ear canal and eardrum, and formal audiologic testing. The audiogram measures the softest sounds you can hear at each pitch, and word recognition testing measures how well you understand speech when it is loud enough to hear — two different things, and the difference between them matters when choosing treatment.
Depending on the findings, further testing may include tympanometry, imaging of the temporal bone or brain, blood work, or genetic testing.
Rehabilitation options
The right option depends on the type and degree of loss:
- Hearing aids amplify sound and are the first line for most sensorineural loss.
- Cochlear implants bypass the damaged inner ear and stimulate the hearing nerve directly. They are for people who get limited benefit from hearing aids, and candidacy criteria continue to expand — including for single-sided deafness.
- Osseointegrated hearing devices transmit sound through the bone of the skull, bypassing the outer and middle ear. These suit conductive and mixed losses, chronically draining ears, and single-sided deafness.
- Surgical repair can restore hearing when the cause is mechanical — for example repairing a perforated eardrum or reconstructing the middle ear bones.
Untreated hearing loss carries consequences beyond the ear, including social withdrawal, difficulty at work, and associations with cognitive decline. That is part of why identifying and addressing it matters even when the loss feels manageable day to day.