The World Health Organization (WHO) estimates that more than five percent of the world’s population has some form of disabling hearing loss.

Doctors will describe someone as having hearing loss when they cannot hear well or at all.

You may have heard the terms “hard of hearing” and “deaf” to describe hearing loss. But what do these terms actually mean? Is there a difference between them? In this article, we answer these questions and more.

Causes

Some diseases or circumstances that can cause deafness include:

• chicken pox
• cytomegalovirus
• mumps
• meningitis
• sickle cell disease
• syphilis
• lyme disease
• diabetes, as studies have shown that people with diabetes are more likely to have some kind of hearing loss http://www.diabetes.co.uk/diabetes-complications/hearing-loss-and-deafness.html
• a treatment for tuberculosis (TB), streptomycin, that is believed to be a key risk factor
• hypothyroidism
• arthritis
• some cancers
• teenagers exposed to second-hand smoke

The inner ear is home to some of the most delicate bones in the body, and damage to the eardrum or middle ear can cause hearing loss and deafness in a range of ways.

Hearing loss vs. deafness

It is important to distinguish between the different levels of hearing loss.

Hearing loss: This is a reduced ability to hear sounds in the same way as other people.

Deafness: This occurs when a person cannot understand speech through hearing, even when sound is amplified.

Profound deafness: This refers to a total lack of hearing. An individual with profound deafness is unable to detect sound at all.

The severity of hearing impairment is categorized by how much louder volumes need to be set at before they can detect a sound.

Some people define profoundly deaf and totally deaf in the same way, while others say that a diagnosis of profound deafness is the end of the hearing spectrum.

How does hearing work?

Sound waves enter the ear, move down the ear or auditory canal, and hit the eardrum, which vibrates. The vibrations from the eardrum pass to three bones known as the ossicles in the middle ear.

These ossicles amplify the vibrations, which are then picked up by small hair-like cells in the cochlea.

These move as the vibrations hit them, and the movement data is sent through the auditory nerve to the brain. The brain processes the data, which a person with functional hearing will interpret as sound.

Types

There are three different types of hearing loss:

1) Conductive hearing loss

This means that the vibrations are not passing through from the outer ear to the inner ear, specifically the cochlea. This type can occur for many reasons, including:

• an excessive build-up of earwax
• glue ear
• an ear infection with inflammation and fluid buildup
• a perforated eardrum
• malfunction of the ossicles
• a defective eardrum

Ear infections can leave scar tissue, which might reduce eardrum function. The ossicles may become impaired as a result of infection, trauma, or fusing together in a condition known as ankylosis.

2) Sensorineural hearing loss

Hearing loss is caused by dysfunction of the inner ear, the cochlea, auditory nerve, or brain damage.

This kind of hearing loss is normally due to damaged hair cells in the cochlea. As humans grow older, hair cells lose some of their function, and hearing deteriorates.

Long-term exposure to loud noises, especially high-frequency sounds, is another common reason for hair cell damage. Damaged hair cells cannot be replaced. Currently, research is looking into using stem cells to grow new hair cells.

Sensorineural total deafness may occur as a result of congenital deformities, inner ear infections, or head trauma.

3) Mixed hearing loss

This is a combination of conductive and sensorineural hearing loss. Long-term ear infections can damage both the eardrum and the ossicles. Sometimes, surgical intervention may restore hearing, but it is not always effective.

Deafness and speech

Hearing loss can affect speech ability depending on when it occurs.

Prelingual deafness

This is an inability to fully or partially hear before learning how to utter or understand speech.

An individual with prelingual deafness was born with a congenital deformity or will have lost hearing during infancy.

In the majority of cases, people with prelingual deafness have hearing parents and siblings. Many are also born into families who did not already know sign language. They consequently also tend to have slow language development. The few who were born into signing families tend not to face delays in language development.

If children with prelingual deafness are given cochlear implants before the age of 4 years, they can acquire oral language successfully.

Oral language and the ability to use social cues are very closely interrelated. That is why children with hearing loss, especially those with severe symptoms, may not only experience delayed language development, but also slower social development.

As a result, children with prelingual deafness risk becoming socially isolated, unless they attend a school that has a well-run special needs department with other children who have the same condition.

Children who identify with a “deaf subculture,” or those who have learned how to use sign language, might feel less isolated. However, some young people might experience isolation if their parents have not yet learned sign language.

There are cases of children with profound deafness who find themselves on the outer fringes of their hearing peers’ social circles while not being fully accepted by peers with total deafness, due to a lack of fluency in sign language.

Post-lingual deafness

Most people with hearing loss have post-lingual deafness. They acquired spoken language before their hearing was diminished. A medication side effect, trauma, infection, or disease may have caused losing their sense of hearing.

In most people with post-lingual deafness, hearing loss onsets gradually.

Household members, friends, and teachers may have noticed a problem before they acknowledged the disability. Depending on the severity of hearing loss, the individual may have had to use hearing aids, receive a cochlear implant, or learn how to lip-read.

People who experience hearing loss face different challenges, depending on when it occurs and how long it takes to develop. They might have to become familiar with new equipment, undergo surgery, learn sign language and lip reading, and use various communication devices.

A feeling of isolation is a common problem, which can sometimes lead to depression and loneliness. A person with post-lingual hearing loss also has to face the often-distressing process of coming to terms with a disability. The condition may also pose challenges for household members, loved ones, and close friends, who have to adapt to the hearing loss.

Miscommunication can place a strain on relationships, not only for the person with the hearing impairment, but also the people around them. If the hearing loss is gradual and has not yet been diagnosed, family members may mistakenly believe that the individual with the condition is becoming more distant.

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