4.8 • +11k Ratings
Save
Print
Edit
Auditory or hearing defects cause partial or total hearing impairment. Hearing loss is defined as the reduced ability to perceive sounds. The severity or degree of hearing loss is categorised according to the increase in the intensity of sound above the normal level required for the person to detect it.
There are three types of hearing loss: conductive, mixed, and sensorineural. Conductive hearing loss is associated with sound problems in the outer or middle ear, sensorineural hearing loss with damage to the auditory nerve itself, and mixed hearing loss has both conductive and sensorineural elements.
Common problems may include blockage in the inner ear, eardrum deformation, fluid in the eardrum, etc.
Ageing, injury, noise exposure, genetics, and viral diseases are the most common causes of hearing loss.
Congenital hearing defects are caused by congenital cardiovascular diseases associated with structural defects of the heart that are almost always present from birth. These structural defects usually involve the walls, valves, arteries, or veins near the heart. Some congenital cardiovascular diseases cause hearing defects, as they reduce blood flow in the body, including to the ear, which damages different parts of the auditory system.
These types of hearing loss are permanent but can be managed using amplification devices such as hearing aids.
Around 80% per cent of congenital hearing loss is caused by defects related to the structure of membranes in the inner ear and, more specifically, the cochlea. A minority of congenital hearing loss is caused by the deformation of the bony labyrinth in the inner ear. If the problem causing hearing defects is the structure of the cochlea, cochlear implants or hearing aids are used for treatment, as shown in figure 1.
Figure 1. Cochlear implant.
Meniere’s disease is related to the pressure on the inner ear. Some causes of Meniere’s disease include fluid drainage, abnormal immune responses, or viral infections. The disease usually only affects one ear but can affect both. It is a progressive disease that can cause either temporary or permanent hearing loss that worsens over time. It also results in sudden side effects like a spinning sensation and ringing noises in the ear.
Treatments include hearing aids, pressure therapy, and surgery to reduce the level of fluid in the inner ear to relieve the pressure.
An acoustic neuroma is a progressive, noncancerous tumour that is located on the nerve connecting the inner ear and the brain. The tumour may apply pressure on the nerve, which may lead to hearing loss, balance problems, or tinnitus, which is a ringing noise in the ear.
If the tumour is projected to cause hearing problems, it is usually surgically removed.
Down syndrome is caused when a person is born with an extra copy of the 21st chromosome. This condition sometimes causes heart defects, which may also affect hearing. In the majority of adults with down syndrome, the condition causes conductive hearing loss due to narrow ear canals without affecting the heart. People with down syndrome, therefore, usually have regular hearing tests and sometimes use hearing aids.
Vestibular neuritis occurs when the nerve responsible for sending motion and balance signals to the brain is inflamed or swollen. Labyrinthitis, on the other hand, is the result of the labyrinth, a spiral-shaped canal filled with fluid in the inner ear, being inflamed. Both conditions are usually caused by a viral infection. Labyrinthitis affects both hearing and balance and is treated by physical therapy to help restore balance and treat the underlying viral condition.
This is a very common form of vertigo caused by a head injury or by debris collected in the inner ear at the semi-circular canals. Vertigo disease has side effects such as dizziness and head spinning. Treatments include the canal repositioning technique, which moves particles from the semi-circular canals to the vestibule, a larger area that can absorb them. The particles can also be moved surgically, using a plug to block fluid flow in the area.
This condition is relatively rare and occurs where the bony area covering the semi-circular canal is either absent or deformed (see figure 2). Symptoms include hearing loss, balance problems, and dizziness. This condition can be treated surgically to fill or reform the area of the missing bone.
Figure 2. Superior semi-circular canal.
Hearing loss is usually progressive, and several symptoms or signs may identify when someone is experiencing it. The first sign of hearing loss is difficulty hearing weak sounds. This may be due to age-related hearing loss. Another common sign is the inability to hear high-pitched sounds, such as birdsong. The inability to have conversations in crowded places due to being unable to differentiate speech may also indicate hearing loss.
Hearing loss tests are used to identify hearing conditions for either hearing loss or balance problems. When structural defects are causing hearing problems, usually imaging is used for proper diagnoses such as computed tomography, CT scans, magnetic resonance imaging, or MRI. For hearing issues, the following tests are performed:
Balance testing is more complex, as it involves a series of examinations to properly diagnose one of the following underlying conditions:
The severity of the hearing loss is classified based on the range of frequencies that can be heard compared to what can be heard by a person with a normal hearing range. Sound is measured in decibels, a measuring unit of loudness. The larger the decibel, the louder the sound. If the patient can only hear at a large number of decibels, they cannot hear quiet sounds and thus are experiencing some hearing loss.
See also the table below.
Degree of hearing loss | Hearing loss range (dB HL) |
|---|---|
Normal | –10 to 15 |
Slight | 16 to 25 |
Mild | 26 to 40 |
Moderate | 41 to 55 |
| Moderate to Severe | 56 to 70 |
Severe | 71 to 90 |
Profound | 91+ |
Hearing loss can be divided into three types: cognitive, sensorineural, and mixed.
There are a variety of factors that can cause hearing defects or hearing loss.
Structural defects can be tested using a CT scan or MRI, but there are also some other physical tests to identify hearing problems.
Hearing loss is classified into categories depending on the severity.
Some common hearing problems are Meniere’s disease, otosclerosis, presbycusis, acoustic neuroma, and autoimmune inner ear disease.
Yes, it does in the majority of people.
Inability to hear high-pitched sounds, inability to hear weak sounds, and being unable to have conversations in a loud environment.
Defects that cause partial or total hearing impairment.
Mixed, conductive, and sensorineural hearing loss.
Be perfectly prepared on time with an individual plan.
Test your knowledge with gamified quizzes.
Create and find flashcards in record time.
Create beautiful notes faster than ever before.
Have all your study materials in one place.
Upload unlimited documents and save them online.
Identify your study strength and weaknesses.
Set individual study goals and earn points reaching them.
Stop procrastinating with our study reminders.
Earn points, unlock badges and level up while studying.
Create flashcards in notes completely automatically.
Create the most beautiful study materials using our templates.
Sign up to highlight and take notes. It’s 100% free.
