Conductive Hearing Loss

How conductive hearing loss works

Hearing has two stages. First, sound waves are funneled down the ear canal, vibrate the eardrum, and are amplified by three small bones, the malleus, incus and stapes. Second, the inner ear (cochlea) turns those vibrations into nerve signals.

Conductive loss is a problem with the first stage. The inner ear and nerve still work, which is why sound conducted directly through the skull bone is heard normally. When both stages are affected, it is called mixed hearing loss.

Symptoms

• muffled or quiet sounds, usually in one ear
• a feeling of fullness or blockage
• your own voice or chewing sounding loud (autophony)
• hearing better in noisy places (paracusis, typical of otosclerosis)
• sometimes ear pain, discharge or ringing in the ear
• in children, inattention, speech delay or turning up the volume

Conductive loss alone usually reaches a maximum of about 60 decibels. It makes speech quiet rather than distorted.

Causes

Outer ear

• Earwax impaction, the most common cause in adults
• swimmer's ear (otitis externa) with a swollen canal
• a foreign object, especially in children
• bony growths in the canal (exostoses) in cold-water swimmers

Middle ear

• Fluid behind the eardrum (otitis media with effusion), the most common cause in children, often after a cold or ear infection
• Acute otitis media, a middle ear infection
• Eustachian tube dysfunction, causing negative pressure
• Perforated eardrum from infection, injury or pressure changes
• Otosclerosis, where abnormal bone fixes the stapes; often runs in families and may worsen in pregnancy
• Cholesteatoma, a skin cyst that erodes the bones
• damage to the ossicles from trauma or chronic infection
• congenital malformations of the ear canal or bones

Conductive vs sensorineural hearing loss

See sensorineural hearing loss for the other type.

Diagnosis

• Otoscope exam to look for wax, fluid, perforation or a cholesteatoma.
• Tuning fork tests (Weber and Rinne) to separate conductive from sensorineural loss.
• Pure-tone audiogram: shows an "air-bone gap", where hearing through bone is better than through air.
• Tympanometry: measures how well the eardrum moves. A flat trace suggests fluid.
• CT scan of the temporal bone if cholesteatoma, malformation or ossicle damage is suspected.

Treatment

• Earwax removal: softening drops, irrigation or microsuction. Do not use cotton swabs or ear candles.
• Watchful waiting for middle ear fluid in children for about 3 months, as most clears on its own.
• Ear tubes (tympanostomy tubes) for persistent fluid with hearing loss.
• Antibiotics for some acute infections.
• Tympanoplasty to repair a perforated eardrum that has not healed in about 3 months.
• Stapedotomy for otosclerosis, replacing the fixed stapes with a tiny prosthesis.
• Surgery to remove cholesteatoma and reconstruct the bones.
• Hearing aids, including bone-conduction devices, which bypass the middle ear completely.

Outlook

Most conductive hearing loss can be improved substantially. Children with temporary fluid usually recover fully. Untreated long-term loss in young children can affect speech and learning, so persistent loss should be checked.

Frequently asked questions

What are the symptoms of conductive hearing loss?

Sounds seem muffled or quiet, often in one ear, and the ear may feel full or plugged. Your own voice can sound louder than usual. Some people hear speech better in noisy places. Pain, discharge or dizziness point to an infection or eardrum problem.

Can conductive hearing loss be cured?

Often, yes. Wax removal, treatment of fluid or infection, eardrum repair and stapes surgery can restore hearing in many cases. When surgery is not suitable, hearing aids work well because the inner ear is usually healthy.

What is the most common cause of conductive hearing loss?

In adults, impacted earwax is the most common cause. In children, it is fluid behind the eardrum after colds and ear infections, known as otitis media with effusion or glue ear.

Is conductive hearing loss permanent?

Not usually. Most causes are temporary or treatable. Permanent loss can occur with chronic infection, cholesteatoma damage or malformations, but surgery or bone-conduction hearing aids can still improve hearing in many of these cases.