There are two main types of hearing loss; acquired hearing loss and congenital. As the names themselves suggest, acquired hearing loss is caused due to external factors that are acquired by an individual. For example, injury to the ear, fever, sudden exposure to very loud noise, unsuitable medication, and diets. Whereas, congenital hearing loss is hearing loss that occurs on its own due to family line or birth.

Congenital Hearing Loss

Age
The term for age-related hearing loss is called presbycusis. Presbycusis comes gradually as an individual gets older. Age-related hearing loss usually affects both ears equally. Due to the progressive nature of the loss, a person with presbycusis may not be aware that they have partially lost their hearing. They may also experience symptoms of the diseases such as tinnitus, lack of coordination and lack of responsiveness.

Heredity
More than half of hearing loss cases in children are caused by deafness due to genetics. There are situations when a gene does not develop as expected. This is referred to as a mutation. While certain mutations run in families, others do not. When several members of the same family experience hearing loss, it is referred to as "familial" hearing loss.

To put it in another way, it's a family affair. Connexin 26 is a protein that plays a critical part in the operation of the cochlea, and the GJB2 gene is the only gene that encodes for this protein. In some groups, the GJB2 gene has a mutation in roughly 40% of newborns hence causing hearing impairment and hereditary damage to the cochlea.

Birth conditions
Conditions like premature birth, low birth weight, ear deformities at birth, jaundice, and issues with the Rh factor, the infant's lack of oxygen, also known as anoxia, are all capable of causing hearing loss in newborns. Even ear deformities such as internal tumors or underdeveloped parts of the middle or inner are a major cause of hearing loss.

Congenital cytomegalovirus (CMV) infection
A prominent contributor to sensorineural hearing loss is CMV infection which accounts for 15% to 25% of all clinically significant hearing loss found in children. Even in infants without symptoms at birth, CMV is often shown to result in hearing loss. The most frequent infectious cause of hearing loss in India is cytomegalovirus, or CMV. CMV affects about 1 in 100 infants worldwide.

Acquired Hearing Loss

Injury
Results from physical damage such as a perforated eardrum, traumatic brain injury (TBI), or skull fracture, among other illnesses. Sudden fluctuations in air pressure, such as those that happen when an aeroplane descends, can even cause hearing loss like sensorineural hearing loss. If you experience head trauma and notice a change in your hearing, make an appointment with your audiologist at the earliest.

Infection or Disease
Diseases like measles, mumps, scarlet fever and meningitis are well-known causes of hearing loss. Typically, viruses cause sensorineural hearing loss, however, a virus like HIV can lead to conductive hearing loss through bacterial and fungal infections caused in your inner ear, which become more aggressive following the immunosuppression caused by that virus.

Ear infection, abnormal bone growths and even tumors. In the outer or middle ear, any of these can cause hearing loss, ruptured eardrum (tympanic membrane perforation), loud blasts of noise, sudden changes in air pressure, poking your eardrum with an object, can affect your hearing. Coronary artery disease (heart disease) and strokes may also be considered as causes of deafness.

Noise induced hearing loss
Sudden exposure to a blast of loud noises is a common cause of hearing loss, especially to those who work in very loud environments like the aviation industry or factories, or at construction sites. The impact of a single loud noise on the inner ear (Cochlea) can be severe, and cause either temporary or permanent hearing loss. Even listening to loud music for prolonged durations of time can overwork and kill the hair cells in your Cochlea causing gradual hearing loss.

Side effects of medication
The 5 most everyday medicines that are proven to cause hearing loss are: Aspirin, Nonsteroidal Anti-Inflammatory Drugs, Antibiotics and Chemotherapy Drugs. Naturally, the risk of hearing loss and other side effects increases if a patient self-administers too much aspirin without a doctor's prescription.

Temporary hearing loss caused by aspirin is often only experienced at high doses, or 8 to 12 pills per day. Ibuprofen is an example of an NSAID pain reliever that might reduce blood flow to the cochlea, an organ in the inner ear that aids in hearing, which may affect how well it performs.

The most often prescribed class of antibiotics, aminoglycosides, exposes patients to a 20% to 60% likelihood of permanent hearing loss. Hearing loss causes have also been linked to the chemotherapy (cancer) medicines cisplatin, carboplatin, and bleomycin.

Conclusion

Drug and alcohol usage during pregnancy, maternal hyperglycemia, and high blood pressure during pregnancy are causes of hearing loss in infants. Expecting mothers are often advised to not drink alcohol or consume any amount of non-prescribed drugs.

Sometimes during the delivery of infants, the doctors might accidentally use excessive force to pull out the infant, which can damage the fragile hearing organs and certain parts of the brain, thereby causing hearing impairment.

As a precautionary measure to check congenital hearing loss, it is highly suggested to parents to get a BERA (Brainstem Evoked Response Audiometry) test done to their infants, as soon as they’re born, in order to help their children get appropriate support for hearing in their early age of development.

Also Read: Conductive Hearing Loss

Sensorineural Hearing Loss 

FAQs

What are the main causes of hearing loss?
Hearing loss can be attributed to aging, excessive noise, various infections, and heredity. Other potential causes include injury, earwax build-up, and ototoxic drugs.

What are the 4 types of hearing loss?
Hearing loss can range from mild to severe cases. There are mainly 3 types of hearing loss
1. Conductive Hearing Loss
2. Sensorineural Hearing Loss
3. Mixed Hearing Loss
4. dys-synchrony 

How can I stop hearing loss?
Preserve your ears from loud, uplifting sounds and do not stick anything in your ears. Regular checkups and early treatment of infections also reduce the risk of further damage, she said.

Which deficiency causes hearing loss?
Vitamin B12 and folate deficiencies are linked to hearing loss. Low magnesium or zinc levels may also affect hearing health.

What foods can cause hearing loss?
High sugar, high sodium, and processed foods may damage hearing over time. Excess caffeine and alcohol can also impact inner ear function.