Up to 3 in 1,000 babies (less than 1 percent) are born with some kind of hearing loss in the United States each year. When a baby is born with hearing loss, it’s called congenital hearing loss. Hearing loss also can develop later in babies or during childhood or adulthood.

Nationally representative data from NHANES provide compelling evidence that hearing loss ≥25 dB affects 3% to 5% of adolescents and hearing loss >15 dB affects 15% to 20% of adolescents.

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Percentage of hearing handicap can be calculated by the following formula:- Degree of handicap: The average pure tone hearing level in the 3 speech frequencies 500, 1000 and 2000Hz is calculated. If this average is ‘X’, then 25 is deducted from it e.g. X-25. This value is multiplied by 1.5.

Mutations in GJB2 are the commonest cause of severe-to-profound autosomal recessive congenital hearing loss in many populations.

Sometimes, hearing and visual problems are missed because of diagnostic overshadowing, that is, behaviors resulting from hearing and visual problems may be considered part of the symptoms of autism, such as lack of attention, speech problems, lack of eye contact or shading of the eyes, and clumsiness.

Sensorineural loss is the most common type of hearing loss. It can be a result of aging, exposure to loud noise, injury, disease, certain drugs or an inherited condition.

Approximately 80% of prelingual deafness is genetic, most often autosomal recessive and nonsyndromic. The most common cause of severe-to-profound autosomal recessive nonsyndromic hearing loss in most populations is mutation of GJB2.

Hearing loss has many causes. 50% to 60% of hearing loss in babies is due to genetic causes. There are also a number of things in the environment that can cause hearing loss.

The causes of nonsyndromic hearing loss are complex. Researchers have identified more than 90 genes that, when altered, are associated with nonsyndromic hearing loss.

Genetic factors make some people more susceptible to hearing loss than others. Their genes make them more predisposed to hearing loss due to ageing or induced by noise, drugs or infections. It is estimated that the causes of age-related hearing loss are 35-55% genetic.

Temporary or permanent threshold shift Exposure to loud sounds for any length of time causes fatigue of the ear’s sensory cells, resulting in temporary hearing loss or tinnitus (a ringing sensation in the ear). This is termed a temporary threshold shift (temporary loss of hearing).

There are two known biological mechanisms of NIHL from excessive sound intensity: damage to the structures called stereocilia that sit atop hair cells and respond to sound, and damage to the synapses that the auditory nerve makes with hair cells, also termed “hidden hearing loss”.

Threshold of Pain. The level of sound at which the listener begins to feel physical pain. This occurs between approximately 115 and 140 dB.

Signs and symptoms of hearing loss may include:

• Muffling of speech and other sounds.
• Difficulty understanding words, especially against background noise or in a crowd.
• Trouble hearing consonants.
• Frequently asking others to speak more slowly, clearly and loudly.
• Needing to turn up the volume of the television or radio.

Use the 60/60 rule when listening to music through headphones to prevent hearing damage: only turn your device volume up to 60% and listen for no more than 60 minutes per day. With loud concerts, music blaring through earphones and noisy workplaces, noise injury is a major, and preventable, cause of hearing loss.

In humans and other mammals, damaged sensory hair cells in the inner ear are unable to divide or regenerate themselves, and there are no drugs that will help restore lost hearing. As a result, most cases of hearing loss (90 percent) are permanent.

Once damaged, your auditory nerve and cilia cannot be repaired. But, depending on the severity of the damage, sensorineural hearing loss has been successfully treated with hearing aids or cochlear implants. There is, however, the possibility that your hearing loss isn’t reversible.

MRI scans use a magnetic field and radio waves to create computerized, three-dimensional images of the ear and the nerve that carries signals from the inner ear to the brain. An MRI scan may reveal a buildup of fluid or inflammation in the inner ear or a growth on the nerve.

Symptoms of Severe Hearing Loss

1. Pain in one or both ears.
2. Dizziness or vertigo.
3. Ringing in the ears, called tinnitus.
4. Pressure or fullness in one or both ears.

Your treatment may include:

1. Balance retraining exercises (vestibular rehabilitation). Therapists trained in balance problems design a customized program of balance retraining and exercises.
2. Positioning procedures.
3. Diet and lifestyle changes.
4. Medications.
5. Surgery.