Deafness, hearing loss, or hearing impairment refers to the partial or complete inability to hear sounds. Symptoms of deafness may be mild, moderate, or severe.
Hearing loss refers to that which is greater than 40 decibels (dB) in adults and 30 dB in children. The majority of people living with hearing loss live in low and middle-income countries.
A person with hearing impairment may find it difficult to understand speech, especially if there is a lot of loud noise, while those with moderate deafness may require a hearing aid. People who are severely deaf rely on lip-reading to communicate with others.
According to the World Health Organization, it has been estimated that about 466 million people globally have hearing loss and 34 million of these people are children. Furthermore, over 900 people will have disabling hearing loss by 2050.
Hearing loss often occurs as a result of genetic causes, infectious disease, birth complications, chronic ear infections, use of certain medication, exposure to loud noises, and aging.
About 1.1 billion young people between the ages of 12-35 are at an increased risk of developing hearing loss due to exposure to noise in recreational settings.
The use of hearing aids, cochlear implants, sign language are other forms of assistive devices, and educational support can help people with deafness live healthy, active lives.
Deafness and Hearing Loss
A person with a hearing threshold of 25 dB or less is said to have hearing loss. Hearing loss can be described as mild, moderate, severe, or profound.
It can affect a single ear or both ears and results in the inability to hear conversational speech or loud sounds. People with hearing loss ranging from mild to severe are often referred to as “hard of hearing”.
Deafness is used to describe people with profound hearing loss, which implies very little or no hearing. Deaf people often communicate using sign language.
Causes of Deafness
To understand the causes of deafness and hearing loss, it is important to understand how hearing works.
The ear consists of three major components: the outer ear, middle ear, and inner ear. Sound waves passing through the outer ear cause vibrations at the eardrum.
The eardrum and three small bones of the middle ear – called the hammer (malleus), anvil (incus) and stirrup (stapes) – amplify the vibrations as they travel to the inner ear. The vibrations from the middle ear pass through fluid in a snail-shaped structure in the inner ear, also known as the cochlea.
Thousands of tiny hairs attached to the cochlea help translate sound vibrations into electrical signals that are transmitted to the brain, which turns these signals into sounds.
Deafness and hearing loss may occur as a result of congenital causes. It may be due to hereditary factors or complications during pregnancy and childbirth.
Congenital causes include:
- Low birth weight
- Syphilis, maternal rubella, or certain other infections during pregnancy
- Inappropriate use of particular drugs during pregnancy
- Birth asphyxia
- Severe jaundice in the neonatal period, resulting in damage to the hearing nerve in a newborn infant.
Deafness may also occur as a result of acquired causes. These include:
- Chronic ear infections
- Infectious diseases such as meningitis, measles, and mumps
- The use of certain medicines, such as those used in the treatment of neonatal
- collection of fluid in the ear
- Infections like malaria, drug-resistant tuberculosis, and cancers;
- Excessive noise like occupational noise such as that from machinery and explosions
- Trauma to the head or ear
- Recreational exposure to loud noise such as that from use of audio devices at high volumes and for prolonged periods and regular attendance at concerts, nightclubs, bars, and sporting events;
- Wax or foreign bodies obstructing the ear canal.
- Aging which can lead to degeneration of sensory cell
Chronic otitis media is can cause in children.
Signs and Symptoms of Deafness
Signs of deafness and hearing loss may include:
- Muffling of speech and other sounds
- Difficulty hearing consonants
- Difficulty understanding words, especially in a crowd or against background noise
- Needing to increase volume of the television or radio
- Asking others to speak more slowly, and loudly
- Avoidance of some social settings
- Withdrawal from conversations
A doctor would conduct a series of tests to confirm the diagnosis. These tests include:
- Physical exam: The doctor will look in the ear for possible causes such as earwax or inflammation from an infection. The doctor will also look for any structural damage that may cause hearing loss.
- General screening tests: The doctor may use the whisper test by asking the patient to cover one ear at a time to see how well they hear words spoken at various volumes and response to other sounds. If the doctor suspects issues with hearing, they may refer the patient to an ear, nose, and throat specialist (ENT)
- Tuning fork tests: This is also known as the Rinne tests. Tuning forks are two-pronged, metal instruments that produce sounds when struck. The doctor can detect hearing loss by using simple tuning forks. This evaluation may also reveal the area of the ear the damage has occurred.
- Audiometer tests. This procedure is carried out by an audiologist and requires that the patient wears headphones. A range of sounds is presented to the patient at various tones, and the patient has to signal each time a sound is heard.
Each tone is presented at various volumes so that the audiologist can determine at which point the sound at that tone is no longer detected. Audiometer tests are also carried out with words.
The audiologist presents words at various tones and decibel levels to determine where the ability to hear stops.
Treatment options for deafness and hearing loss include:
- Hearing aids: These can be helpful for hearing loss due to damage to the inner ear. The patient can discuss with the audiologists the potential benefits of hearing aids and the different options available.
- Removing wax blockage: Earwax blockage is a common and reversible cause of hearing loss. The doctor may remove earwax using suction or a small tool with a loop on the end.
- Surgical procedures: Surgery may be required to treat some types of hearing loss, such as abnormalities of the eardrum or bones of hearing.
- Cochlear implants: These devices may be necessary in cases of severe hearing loss where conventional hearing aids don’t work. Unlike hearing aids, which amplify sounds and direct them into the ear canal, cochlear implants bypass the damaged part of the ear and directly stimulate the hearing nerve.