The two types of hearing loss are conductive and sensorineural. Conductive hearing loss happens when sound is physically blocked from reaching the inner ear. Sensorineural hearing loss happens when the inner ear itself, or the nerve that carries sound signals to the brain, is damaged. A third category, mixed hearing loss, describes cases where both types are present in the same ear.
Conductive Hearing Loss
Conductive hearing loss occurs when something prevents sound waves from traveling through the outer ear canal, the eardrum, or the three tiny bones of the middle ear. Think of it as a mechanical problem: the equipment that normally funnels and amplifies sound isn’t working properly. Because the inner ear is still functioning, this type is often treatable or even fully reversible.
Common causes include earwax buildup, fluid behind the eardrum (sometimes called “glue ear”), ear infections, and foreign objects lodged in the ear canal. More serious causes involve damage to the small bones of the middle ear. A head injury can dislocate these bones, and a condition called otosclerosis causes abnormal bone growth that gradually locks one of them in place, preventing it from vibrating. Some studies suggest that conductive hearing loss from treatable factors like ear infections and earwax impaction is the most common cause of hearing loss worldwide.
Because the blockage sits between the outside world and a healthy inner ear, treatment often focuses on removing or bypassing the obstruction. Earwax can be cleared, infections can be treated, and damaged middle ear bones can sometimes be surgically repaired. When surgery isn’t an option, bone conduction hearing devices offer another route: a small processor transmits sound vibrations directly through the skull bone to the inner ear, skipping the outer and middle ear entirely.
Sensorineural Hearing Loss
Sensorineural hearing loss is the more common and typically more permanent type. It originates in the inner ear, where thousands of microscopic hair cells convert sound vibrations into electrical signals for the brain. When these hair cells are damaged or destroyed, they don’t regenerate. The result is a permanent reduction in hearing ability that usually worsens over time.
The most frequent causes are aging and noise exposure. Years of loud sound, whether from occupational noise, concerts, or headphones, gradually destroys hair cells. Age-related changes do the same thing more slowly. Other causes include certain medications that are toxic to the inner ear, genetic conditions, viral infections, and head trauma.
Unlike conductive loss, sensorineural hearing loss can’t be fixed by removing a blockage or repairing a bone. Hearing aids are the primary treatment for most people. They amplify sound so the remaining hair cells can pick up more of it. For severe cases where hearing aids aren’t enough (typically when hearing thresholds exceed 70 to 80 decibels), cochlear implants become an option. These surgically placed devices bypass the damaged hair cells entirely and stimulate the auditory nerve directly.
How the Two Types Feel Different
Conductive hearing loss tends to make sounds quieter across the board, almost like wearing earplugs. You might notice you can still hear your own voice clearly, or that sounds seem normal once they’re loud enough. It often affects one ear more than the other and may come on suddenly, especially when caused by an infection or wax buildup.
Sensorineural hearing loss distorts sound quality, not just volume. Words may sound muffled or unclear even when they’re loud enough to hear. High-pitched sounds like children’s voices or birdsong often disappear first. Background noise becomes much harder to filter out, so conversations in restaurants or crowded rooms feel disproportionately difficult. This type usually develops gradually in both ears, which is why many people don’t realize it’s happening until it’s fairly advanced.
How Audiologists Tell Them Apart
A standard hearing test measures how well you hear sounds delivered two different ways: through the air (via headphones) and through bone vibration (via a small device placed behind your ear). Air conduction tests the entire pathway from outer ear to brain. Bone conduction bypasses the outer and middle ear and sends vibrations straight to the inner ear.
If both scores are equally reduced, the problem is in the inner ear or auditory nerve, pointing to sensorineural loss. If bone conduction hearing is normal but air conduction is reduced, there’s a gap between the two scores. That gap means something is blocking sound before it reaches a healthy inner ear, which is the hallmark of conductive loss. When both scores are reduced but air conduction is worse than bone conduction, that gap signals a mixed hearing loss with both types present.
When Hearing Loss Is an Emergency
Most hearing loss develops slowly, but sudden sensorineural hearing loss is a medical emergency. It’s defined as a drop of at least 30 decibels appearing within 72 hours, and it typically strikes one ear. You might wake up one morning and realize you can’t hear out of one side, or notice it when you hold a phone to that ear.
Timing matters enormously. Treatment started within two weeks of symptom onset produces significantly better results than treatment started later. After that 14-day window, the chances of recovering lost hearing drop sharply. If you experience a sudden, noticeable loss of hearing in one ear, getting evaluated within days rather than weeks can make the difference between recovery and permanent damage.
Mixed Hearing Loss
Mixed hearing loss is exactly what it sounds like: a combination of conductive and sensorineural problems in the same ear. Someone might have age-related inner ear damage and then develop an ear infection or wax buildup on top of it. The conductive component is often treatable, which can restore some hearing, but the underlying sensorineural damage typically remains. Treatment plans usually address the conductive issue first, then reassess how much sensorineural loss is left to manage with hearing aids or other devices.