Understanding Hearing Loss: Causes, Types and Treatment Options
Hearing loss can affect people of all ages. It may develop gradually over several years or appear suddenly. It can affect one ear or both ears and may be temporary, permanent, stable or progressive.
Because hearing loss has many possible causes, an accurate diagnosis is important. Some conditions, such as impacted earwax or fluid behind the eardrum, may be treatable. Other forms of hearing loss may be permanent but can often be managed with hearing aids, assistive devices, cochlear implants or other treatments.
How Does Hearing Work?
The ear has three main sections: the outer ear, middle ear and inner ear. Each plays a specific role in turning sound waves into information the brain can understand.
The outer ear collects sound. Sound waves enter the ear canal and travel toward the eardrum.
The middle ear amplifies sound vibrations. Sound causes the eardrum to vibrate. These vibrations move three tiny bones called the malleus, incus and stapes.
The inner ear converts movement into electrical signals. The middle-ear bones transmit vibrations to the cochlea, a fluid-filled, spiral-shaped structure in the inner ear. Movement within the cochlea bends specialized sensory hair cells.
The brain interprets the sound. The hair cells convert movement into electrical signals. The auditory nerve carries these signals to the brain, where they are recognized as speech, music and other sounds.
Hearing loss can develop when sound is prevented from traveling normally through the outer or middle ear, when structures within the inner ear are damaged, or when the auditory nerve and brain cannot process sound signals normally.
Common Signs of Hearing Loss
Hearing loss is not always immediately noticeable, especially when it develops gradually. Common signs include:
Frequently asking people to repeat themselves
Feeling as though other people are mumbling
Turning up the television, phone or radio
Having difficulty following conversations in restaurants or crowded rooms
Struggling to hear higher-pitched voices or sounds
Hearing better in one ear than the other
Experiencing ringing, buzzing or other sounds in the ears
Feeling tired after conversations because listening requires extra effort
Withdrawing from conversations or social situations
Noticing that speech sounds muffled
Having difficulty determining where a sound is coming from
Family members and friends may notice these changes before the person experiencing them does.
What Causes Hearing Loss?
Hearing loss may result from a problem in the outer, middle or inner ear. It can also involve the auditory nerve or the pathways the brain uses to interpret sound.
Conditions Affecting the Outer Ear
Problems in the outer ear may prevent sound from reaching the eardrum properly. Possible causes include:
Impacted earwax
Swelling or infection in the ear canal
A foreign object in the ear
A growth within the ear canal
An injury
A structural difference present at birth
Many causes of outer-ear hearing loss can be treated after the underlying problem is identified.
Conditions Affecting the Middle Ear
Problems involving middle-ear pressure, fluid drainage or movement of the eardrum and middle-ear bones can interfere with the transmission of sound.
Possible causes include:
Fluid behind the eardrum
Middle-ear infections
A perforated or damaged eardrum
Problems involving the three middle-ear bones
Otosclerosis, which can limit movement of the stapes bone
Benign or malignant growths
Pressure-related injuries caused by flying or scuba diving
Persistent middle-ear fluid is especially common in children and may temporarily reduce hearing.
Conditions Affecting the Inner Ear or Auditory Nerve
Inner-ear or auditory-nerve hearing loss may result from:
Aging
Repeated exposure to loud noise
A single extremely loud sound
Genetic or hereditary conditions
Head injuries
Certain infections
Ménière’s disease
Medications that can damage hearing
Structural differences within the inner ear
Damage to the auditory nerve
The sensory hair cells inside the human cochlea generally do not regenerate after they are damaged. Hearing loss caused by this type of damage is usually permanent.
Noise-Induced Hearing Loss
Exposure to excessive noise is one of the most common preventable causes of hearing loss. Damage may occur after a single explosive sound, such as a firework or gunshot, or after repeated exposure to loud music, machinery, power tools, sporting events and other noisy environments.
The risk depends on both the volume of the sound and the length of exposure. The louder a sound is, the less time it takes to cause damage.
Noise-induced hearing loss cannot currently be reversed with medication or surgery, making prevention especially important. You can help protect your hearing by:
Lowering the volume on personal listening devices
Moving farther away from loud sound sources
Limiting the amount of time spent in noisy environments
Taking listening breaks
Wearing properly fitted earplugs or protective earmuffs
Protecting children’s hearing during concerts, fireworks and other loud events
If you need to shout to be heard by someone nearby, the environment may be loud enough to damage your hearing.
Age-Related Hearing Loss
Age-related hearing loss, also known as presbycusis, typically develops gradually and affects both ears. Someone may be able to hear that another person is speaking but struggle to understand individual words, particularly in rooms with background noise.
Changes in the inner ear, auditory nerve and sound-processing pathways may all contribute. A lifetime of noise exposure, genetics, certain medications and medical conditions such as diabetes and high blood pressure may also affect hearing over time.
Because the change is gradual, many people do not immediately recognize how much hearing they have lost. Routine hearing evaluations can help identify changes and establish a useful baseline.
Genetic and Congenital Hearing Loss
Some people are born with hearing loss, while others inherit genetic changes that cause hearing to decline later in life.
Possible causes include:
Genetic variations affecting the development or function of the inner ear
Certain infections that occur during pregnancy
Complications surrounding birth
Structural differences of the ear
Connexin 26-related hearing loss
Otosclerosis
Genetic conditions such as CHARGE, Treacher Collins, Usher, Waardenburg and Goldenhar syndromes
Not every hereditary form of hearing loss is associated with a recognized syndrome. Genetic counseling or testing may sometimes be recommended based on a patient’s age, symptoms, medical history and family history.
The Three Main Types of Hearing Loss
Hearing loss is generally classified into three primary categories.
Conductive Hearing Loss
Conductive hearing loss occurs when sound cannot travel efficiently through the outer or middle ear.
Possible causes include:
Impacted earwax
An object in the ear canal
Swelling or infection
Middle-ear fluid
A damaged or perforated eardrum
Problems involving the middle-ear bones
Structural differences of the outer or middle ear
Depending on the cause, conductive hearing loss may be temporary and treatable with medication, an office procedure or surgery.
Sensorineural Hearing Loss
Sensorineural hearing loss results from damage to the cochlea, its sensory hair cells or the auditory nerve.
Possible causes include:
Aging
Loud-noise exposure
Genetics
Head injuries
Certain infections
Medications that can damage hearing
Structural differences within the inner ear
Ménière’s disease
This form of hearing loss is usually permanent. Hearing aids, assistive listening devices and, in qualifying cases, cochlear implants may help improve access to sound and speech.
Mixed Hearing Loss
Mixed hearing loss is a combination of conductive and sensorineural hearing loss.
For example, someone with permanent inner-ear hearing loss may also develop temporary middle-ear fluid or impacted earwax. Each component may require a different form of treatment.
Auditory Processing Difficulties
Some people can detect sounds but have difficulty organizing or interpreting them, especially when several sounds occur at once. This may be associated with an auditory processing disorder rather than hearing loss within the ear itself.
Auditory processing difficulties are not generally classified as one of the three primary types of hearing loss. A specialized evaluation may be needed to determine where the communication difficulty is occurring.
How Is Hearing Loss Measured?
Hearing loss may be classified as slight, mild, moderate, moderately severe, severe or profound. The terminology and numerical ranges can vary slightly among hearing-health organizations.
The severity is only one part of the evaluation. Hearing can vary significantly across different pitches. Someone may hear certain frequencies normally while struggling to hear others.
Hearing loss may also be described as:
Unilateral: Affecting one ear
Bilateral: Affecting both ears
Symmetrical: Similar in both ears
Asymmetrical: Different in each ear
Progressive: Becoming worse over time
Sudden: Developing immediately or within a few days
Fluctuating: Improving and worsening over time
Stable: Remaining relatively unchanged
How Is Hearing Loss Diagnosed?
A complete hearing evaluation may include:
A review of symptoms and medical history
A physical examination of the ears
Pure-tone testing to measure the softest sounds a person can hear
Speech testing to evaluate word recognition
Tympanometry to examine eardrum movement and middle-ear function
Additional imaging, balance testing or nerve testing when medically indicated
These results help determine the location, type, pattern and severity of the hearing loss.
How Is Hearing Loss Treated?
Treatment depends on the type and underlying cause of the hearing loss. Options may include:
Professional removal of impacted earwax
Monitoring or treating middle-ear fluid
Medication for certain infections or inflammatory conditions
Repair of an injured or perforated eardrum
Surgery to correct problems involving the eardrum or middle-ear bones
Treatment or removal of an abnormal growth
Hearing aids
Assistive listening and alerting devices
Cochlear implants for qualifying patients
Communication strategies
Auditory rehabilitation
Antibiotics may be prescribed for certain bacterial ear infections. However, antibiotics do not treat viral infections, middle-ear fluid without an active bacterial infection or sensorineural hearing loss.
Cochlear implants may be considered for qualifying children and adults with significant sensorineural hearing loss who receive limited benefit from appropriately fitted hearing aids. Candidacy depends on several factors, including speech understanding and the amount of benefit received from hearing aids.
Ear Tubes and Middle-Ear Fluid
For persistent middle-ear fluid or recurring ear infections, an otolaryngologist may recommend a myringotomy with tympanostomy tube placement.
During this procedure, a small opening is made in the eardrum, and a tiny tube is placed through the opening to ventilate the middle ear. Any fluid present may also be removed during the procedure.
The tube is placed in the eardrum, not inside the Eustachian tube.
When Is Hearing Loss an Emergency?
A sudden change or loss of hearing, especially in one ear, should be treated as a medical emergency. Contact an otolaryngologist immediately or seek urgent medical care. Do not wait to see whether the hearing returns on its own.
Sudden sensorineural hearing loss may develop immediately or over several days. It can sometimes be mistaken for congestion, allergies, an ear infection or impacted earwax. Early diagnosis and treatment may improve the chance of recovering some hearing.
Seek immediate medical attention if hearing loss is:
Sudden or rapidly worsening
Mainly affecting one ear
Accompanied by dizziness or balance problems
Associated with severe ear pain, drainage or bleeding
Accompanied by facial weakness, numbness or other neurological symptoms
Related to a head injury or extremely loud sound
Occurring with fever or signs of a significant infection
Schedule a Hearing Evaluation
If you have noticed a change in your hearing, persistent ringing in your ears or increasing difficulty understanding conversations, schedule an evaluation with one of our otolaryngologists.
A physical examination and comprehensive hearing test can help identify the type, pattern and severity of the problem. Once the cause is better understood, we can recommend an individualized treatment plan to help protect your remaining hearing and improve communication.
