A Guide to the Different Types of Hearing Loss
Hearing loss refers to a partial or total impairment of a person’s hearing ability. It’s one of the most common disabilities around the world and can anyone, regardless of age or gender. There are five main types of hearing loss, and the type of hearing loss depends on what part of the auditory system is affected.
Five Types of Hearing Loss
The main types of hearing impairment include:
- Auditory processing disorders
- Conductive hearing loss
- Sensorineural hearing loss
- Idiopathic hearing loss
- Mixed hearing loss
Let’s discuss each type of hearing loss in a little more detail…
Auditory Processing Disorders
Auditory Processing Disorder (APD), also referred to as Central Auditory Processing Disorder (CAPD), is a term that is used to refer to various disorders that affect the brain, which interferes with the ability of the brain to process auditory information effectively.
People with this type of hearing impairment usually have a normal ear structure, which suggests that each part of their ear functions normally. However, their brain processes the sounds that they hear in an abnormal manner, leading to issues with interpreting and recognizing the sounds they hear.
Researchers suggest that this happens because people with auditory processing disorder have a malfunctioning central nervous system.
This type of hearing loss can occur in both kids and adults. Statistics show that men are twice as likely to be affected by this type of hearing loss compared to females.
The causes of APD include acquired disorders that damage the central nervous system and also involve a combination of genes resulting in neurological disorders that trigger hearing impairment.
The diagnosis of this type of hearing impairment is quite difficult; therefore a number of tests may be used by audiologists to detect APD, including:
- SCAN – one of the most commonly used standardized tests to detect APD. It consists of four subsets: the detection of monaurally single words in background noise, acoustically degraded words, dichotic single words, and sentence stimuli. The test varies as audiologists use different versions depending on the age of the patient.
- Random Gap Detection Test (RGDT) – a standardized test that includes the hearing of stimuli at four different frequencies (500, 1000, 2000 and 4000 Hz). This test assesses how much gap a person has between detecting tones and white noise, and establishes an index of auditory temporal resolution. The greater the index, the greater the likelihood of APD.
- Gaps in Noise Test (GIN) – this test is similar to Random Gap Detection Test as it also establishes an index of auditory temporal resolution based on the detection of white noise by the patient.
- Pitch Pattern Sequence Test (PPT) and Duration Patterns Sequence Test (DPT) – these tests use sounds at a different pitch (either high or low) and at different times (either long or short) respectively, and the patient is asked to describe each sound.
Types of Auditory Processing Disorders
- Presbycusis is one of the most common types of hearing loss, and it is believed to be caused by the combined effects of intrinsic aging of the peripheral or central auditory systems along with the accumulated effects of normal bodily wear and tear. The condition can also be triggered by age-related diseases, possible toxic effects of drugs, chemicals, heredity, and diet.
- Tinnitus is essentially a ringing in the ears or a head noise that most people have experienced at one time or another in their lifetime. Tinnitus can accompany or be associated with loss of hearing, and it can also exist on its own without any hearing loss present.
Conductive Hearing Loss
This type of hearing loss occurs when there is a mechanical disorder with the outer or middle ear that interferes with the peripheral hearing mechanism, and sounds do not reach the inner ear effectively.
The potential causes include a perforated eardrum, ear infection, heredity disorders, wax build-up, the presence of a foreign body, trauma, fluid build-up in the middle ear (i.e., the result of a cold or malfunctioning of the Eustachian tube), and tumor (in very rare cases).
This type of hearing loss usually affects children and indigenous people. Conductive hearing loss can be easily diagnosed depending on the symptoms and signs.
Furthermore, it can also be treated completely with the aid of surgeries and hearing aids including middle ear transplants and bone conduction hearing aids.
Antimicrobials can also be used as a potential treatment if the hearing impairment is the result of an ear infection.
Types of Conductive Hearing Loss
- Otitis Media is a common form of conductive hearing loss. It results from an inflammation in the middle ear; which is the area behind the eardrum. Otitis media is generally associated with the buildup of infected or non-infected fluid.
- Otosclerosis is a disease that involves the middle ear capsule. It specifically affects the movement of the stapes; which are the three tiny bones in the middle ear. Otosclerosis is often described as an abnormal growth of bony tissue in the middle ear.
- A cholesteatoma is a form of skin growth that occurs in the middle ear behind the eardrum. Cholesteatoma can lead to conductive hearing loss.
- Ear wax blockage is one of the most common causes of conductive hearing loss in people of all ages around the world.
- Swimmer's ear or otitis externa is a common infection of the outer ear. Swimmers often get this type of infection as a result of water being trapped in the ear canal.
- A perforated eardrum can be quite painful as it's caused by a rupture or hole in the eardrum. A perforated eardrum can cause temporary hearing loss and along with occasional discharge from your ear.
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Sensorineural Hearing Loss
Sensorineural hearing loss, also referred to as nerve deafness, is the most common type of hearing loss.
It most commonly occurs as the result of damage to the tiny hair cells that vibrate when sound waves hit them and produce chemicals to stimulate the auditory nerve. However, it can also occur when the cochlea (inner ear), and/or the auditory nerves that link the ear and the brain, get damaged.
The causes of sensorineural hearing loss include exposure to loud noise, aging, head trauma, viral infections, autoimmune inner ear disease, diseases such as meningitis and measles, structural malformation of the inner ear, ototoxic drugs, Meniere’s disease, heredity factors, and tumors.
Different medications and medical procedures are used to treat sensorineural hearing loss. When the hearing loss occurs suddenly and is assumed to be a consequence of viral infection, corticosteroids are used. They are also used to help cochlear hair swelling and inflammation after exposure to loud noise.
Furthermore, there are cases when the hearing impairment results due to abrupt changes in air pressure and the liquid compartment ruptures. At such stage, surgery is carried out. Hearing aids are also used to reduce this type of hearing loss when other medications and procedures are ineffective.
It’s important to note that this kind of hearing loss is usually irreversible and medical measures that are utilized only reduce the severity of the impairment.
Types of Sensorineural Hearing Loss
- Waardenburg syndrome is a common form of sensory hearing loss that also affects your appearance. The level of hearing loss associated with the condition varies from moderate to profound.
- Meniere's disease is a common type of sensory hearing loss that is caused by changes in the chemical composition and amount of fluid in the inner ear. This disease usually only affects one ear and can also cause severe dizzy spells, known as vertigo, and loss of hearing. The hearing loss usually fluctuates, but will gradually deteriorate over time.
- Noise-induced hearing loss is caused by overexposure to loud sounds.
Idiopathic Hearing Loss
Idiopathic hearing loss is an unexplained sudden hearing loss. This type of hearing loss usually affects people who are between the ages of 30 to 60 years old. The condition affects both males and females equally.
Although sudden idiopathic hearing loss (SIHL) is called sudden, it's not very likely that a person's loss of hearing happens so abruptly. Sudden hearing loss (SHL) is described as losing greater than 30 decibels of your hearing over at least three contiguous frequencies within three days (72 hours) or less. A more likely scenario would be that the person's hearing loss takes place over a few hours.
Sudden idiopathic hearing loss (SIHL) can affect individual people very differently. SIHL usually affects only one ear, and it is often accompanied by tinnitus, vertigo, or both of those conditions. The amount of hearing a person loses may vary from mild to severe. The loss may also involve different parts of the hearing frequency range.
Although many medical experts believe that sudden hearing loss is generally of an unknown cause, viral disease appears to be the cause for about 60 percent of all cases of SHL. These viruses include influenza type B, mumps, rubella, measles, herpes-1, and infectious mononucleosis. It's possible that there could be a multitude of other causes for SHL including vascular disease, Lyme disease, Meniere's disease, acoustic neuroma, otitis media, exposure to ototoxic medications, tumors, stroke and Cerebrospinal fluid (CSF) leak.
There are various types of treatment that have been used for SIHL including oxygen therapy, vitamin E, antivirals, diuretics, anticoagulants, plasma expanders, and carbogen. However many medical professionals believe that steroids are the best treatment for the condition.
Mixed Hearing Loss
This type of hearing loss is a combination of both conductive and sensorineural hearing loss, resulting in more severe signs and symptoms. Individuals with mixed hearing loss can barely hear sounds.
Physicians treat this type of hearing loss by initially focusing on the conductive component that is causing the hearing loss, as it is usually temporary. Once the disorders causing the conductive hearing loss are treated successfully, audiologists shift their focus towards the issues causing sensorineural hearing loss, as these causes are usually permanent.
After the problems resulting in hearing impairment are treated medically, patients are then prescribed hearing aids.
If you’re suffering from hearing loss, you should seek medical care to determine the underlying cause of your impairment. In many cases, medications, procedures, and/or devices can be utilized to help improve your level of hearing.