Types of Hearing Loss

What Is Hearing Loss?

Hearing loss is a condition that occurs when any part of the auditory system is not working in the normal manner. Also, hearing loss can occur as we gradually age, and that is common.

What Is the Mechanism of Hearing?

The human ear works by collecting the sound in the environment through pinna that passes through the ear canal and strikes the ear drum. Vibrations of the drum are transmitted to the inner ear through the chain of ossicles coupled to the drum. This stimulates hair cells of the organ of Corti. These hair cells act as transducers and convert mechanical energy into electrical impulses, which travel along the auditory nerve to the brain.

What Are the Different Types of Hearing Loss?

The type of hearing loss depends on the part of the auditory system affected. The following are different types:

• Conductive hearing loss.

• Sensorineural.

• Mixed.

What Is Conductive Hearing Loss?

Conductive hearing loss is when there is any obstruction to the conduction of sound waves from the external ear to the inner ear. That is, in this case, the affected part of the auditory system may be the external ear or the middle ear. In this condition, the patient finds it difficult to hear soft sounds.

What Causes Conductive Hearing Loss?

Conductive hearing can be caused for the following reasons:

• Ear Wax- Sometimes, the accumulation of earwax in the ear canal can block the sound waves and hence, cause impaired hearing.

• Foreign Bodies Introduced Into the Ear Canal Like - children may put beads or pebbles in the ear, and sometimes bugs may go inside the ear of adults leading to conductive hearing loss.

• Noncancerous bone growth inside the auditory canal is often linked with cold water swimming.

• Aural Atresia- the defect of the external ear canal at birth seen along with defects of the external ear structure.

• Hole in the eardrum caused by trauma, infection, or severe eustachian tube dysfunction.

• Problems in the eardrum.

• Infection of the middle ear can result in fluid accumulation in place of air, known as Otitis media, commonly seen in children.

• Sometimes the eardrum may collapse to the middle ear bones due to severe pressure imbalance in the middle ear because of poor function of the Eustachian tube.

• Cholesteatoma is the presence of skin cells in the middle ear which is usually not present.

• Damage to middle ear bones.

What Are the Symptoms of Conductive Hearing Loss?

The symptoms of conductive hearing loss are as follows:

• Sudden loss of hearing.

• Difficult to hear soft sounds.

• Pain in the ear.

• Stuffiness in the ear.

• Dizziness.

• Muffled hearing.

• Draining from the ear.

What Is Sensorineural Hearing Loss?

Sensorineural hearing is the hearing loss originating from the inner ear or nerve pathways that run from the inner ear to the brain. The sound from the outer ear to the inner ear from where the signals are sent to the brain. The cochlea of the inner ear has tiny hair-like cells which are damaged in case of sensorineural hearing loss. It is the most common type of permanent hearing loss and, in most instances, cannot be medically or surgically treated.

What Causes Sensorineural Hearing Loss?

The following are the causes of Sensorineural hearing loss:

• Damage to the auditory nerve.

• Damage to tiny hair cells on the cochlea.

• Viral infections.

• Exposure to loud noise.

• Aging.

• Trauma to the head.

• An abrupt change in air pressure can cause the space that contains inner ear fluid to rupture.

• Vestibular Schwannoma - noncancerous bony growth in the inner ear, which can compress the nerve to the brain.

• Genetic abnormality during the formation of the inner ear.

• Autoimmune conditions in which the body's own cells attack the hair cells of the cochlea.

• Drug intoxication.

What Are the Symptoms of Sensorineural Hearing Loss?

Symptoms may include:

• Difficulty understanding the speech.

• Muffled hearing.

• Tinnitus (ringing sound in one or both ears)

• Sudden loss of hearing.

• Dizziness.

• Stuffiness in the ear.

What Is Mixed Hearing Loss?

Mixed hearing loss is the combination of both conductive and sensorineural hearing loss, which means the outer, middle, and inner ears are affected in this case. There is a conduction block to the sound waves as well as there is damage to either hair cells of the cochlea or the auditory nerve. The sensorineural component may be permanent, but the conductive part may be corrected.

What Causes Mixed Hearing Loss?

The causes of mixed hearing loss include causes of both Conductive and Sensorineural hearing loss and include:

• Aging.

• Birth abnormalities.

• Certain medications.

• Exposure to loud noise.

• Tumors.

• Collection of earwax.

• Trauma to the head.

• Infections.

What Are the Symptoms Of Mixed Hearing Loss?

• Reduced hearing in one (unilateral) or both (bilateral) the ears.

How to Diagnose Hearing Loss?

Even though hearing loss is common in old age people, it is not given much attention, and a proper diagnosis is never made. Impaired hearing can greatly affect one’s quality of living; hence it is always important to reach a diagnosis. If hearing loss is suspected, always consider consulting a specialist as early as possible so that proper treatment is received at the earliest as some conditions could be cured completely depending on the cause and severity.

The different types of tests to diagnose the type of hearing loss include:

• Standard Audiometry - This method is used to make diagnoses in adults and older children. In this test, earphones are placed in each ear through which a range of tones is transmitted- patients are asked to respond when they hear each sound.

• Bone Conduction - This test is used to determine the type of hearing loss. In this test, a device is used which sends vibrations directly to the inner ear or cochlea and not through the outer or middle ear, and if the patient can hear properly, then he has conductive hearing loss. In case the patient can hear well with both earphones and vibrator, then he/she might have a sensorineural hearing loss.

• Word Recognition Test - In this test, the ability to differentiate the speech sounds of various words are evaluated.

• Acoustic Immittance - This test evaluates the condition of the middle ear and related structures.

• Otoacoustic Emissions (OAEs) - Assess the function of the cochlea.

• Auditory Brainstem Response (ABR) - ABRs are procedures done to determine the functioning of neural pathways.

How Can It Be Treated?

The treatment for hearing loss depends on the type and severity of the condition and includes:

• Hearing Aids - Hearing aids are advised in case of damage to the inner ear.

• Removing Earwax- Hearing loss due to wax blockage is reversible.

• Surgery - This is advised in case of any growth in the auditory system and some cases of damage to the eardrum.

• Cochlear Implants- This option is for people with profound hearing loss who had no benefit from the usage of hearing aids. Cochlear implants bypass the damaged parts of the ear and directly send the signal to the nerve.

Conclusion:

Hearing loss can be because of improper functioning or even not functioning of any part of the ear. The part of the ear affected tells what type of hearing loss one is suffering from and the treatment option varies accordingly. The treatment options include either correcting the cause or using prosthetics to correct the hearing. Impaired hearing can affect your day-to-day life, and in some cases, the hearing loss may become permanent too. But, the interference by a physician at the right time will greatly affect the overall prognosis.