Hearing Impairment

You know what hearing is, but what is hearing loss? Hearing loss, or hearing impairment, occurs when there is a problem with one or more parts of the ear or ears (when there is an “impairment” it means that something is not working properly or as it should).

A person who loses his or her hearing may be able to hear some sounds or nothing at all. People may also use the terms deaf, hard of hearing, or deafness when talking about hearing loss.

About three out of every 1000 babies are born with hearing loss, making this disorder the most common birth defect. A hearing problem can also develop later in life.

How Hearing Works

To understand how and why hearing loss occurs, it is helpful to know how the ear works. The ear consists of three sections: the outer ear, the middle ear and the inner ear. These parts work together so you can hear and process sounds. The outer ear, or pinna (the part you can see), picks up sound waves that then travel through the outer ear canal.

When the sound waves reach the eardrum in the middle ear, the eardrum begins to vibrate. When the eardrum vibrates, it moves three tiny bones in the ear. These are called the hammer, anvil, and stirrup, and they help the sound move forward on its journey to the inner ear.

Then, the vibrations travel to the cochlea, a fluid-filled cavity lined with cells that have thousands of tiny cilia on their surfaces. There are two types of hair cells: external and internal. Sound vibrations cause the tiny cilia to move.

The outer hair cells pick up sound information, amplify it (make it louder), and tune it. The inner hair cells send the sound information to the auditory nerve, which then sends it to the brain, allowing you to hear.

Types of hearing loss

There are five different types of hearing loss: conductive, sensory, mixed (conductive and sensory combined), neural and central.

  • Conductive hearing loss – occurs when there is a problem in one part of the outer or middle ear. In most children with conductive hearing loss, the hearing loss is mild and usually temporary, because in most cases medical treatment can help.
  • Sensory hearing loss – occurs when the cochlea does not work properly because the tiny hair cells are damaged or destroyed. Depending on the hearing loss, a child might: hear most sounds (even if they are turned off); hear when it is quiet, but not when it is noisy; hear only some sounds or hear nothing at all. Sensory hearing loss is almost always permanent, and a child’s ability to speak normally may be affected.
  • Neural hearing loss: occurs when there is a problem with the connection between the cochlea and the brain. Neural means related to the nerves; therefore, neural hearing loss implies that the nerve that transmits messages from the cochlea to the brain is damaged.
  • Central hearing loss occurs when the cochlea is functioning properly, but parts of the brain are not. It is a less common type of hearing loss and is more difficult to treat.

What causes hearing loss?

Hearing loss can occur because a person was born with parts of the ear that did not form properly and do not work well. There are other problems that can arise at a later stage due to injury or illness, including

  • having fluid in the middle ear
  • suffer from serious infections, such as meningitis
  • suffer a head injury
  • listening to very loud music, especially with headphones or earphones
  • be repeatedly exposed to loud sounds, such as those from machines

Many children have had ear infections, which can also cause hearing loss. It is rare for an ear infection to cause hearing loss. However, you should see your doctor if you or your parents suspect that you have an infection.

What tests does a doctor perform to diagnose hearing loss?

If a doctor thinks that an infant or child may have hearing loss, he or she will recommend that parents take the child to an audiologist. An audiologist is specially trained to evaluate and help with problems related to hearing loss.

A pediatric audiologist evaluates a child’s hearing through different types of tests. There are even hearing tests for babies. You may have had your hearing tested when you used headphones and had to raise your left or right hand to indicate that you could hear with each ear.

If an audiologist determines that a child has hearing loss, he or she will recommend treatment and suggest that the family work with special equipment. This team can help determine the best method for the child to learn and communicate.

How is hearing loss treated?

The type of treatment depends on the type of hearing loss, its severity and the other needs of the child. Common treatments include medication, surgery, hearing aids, and other assistive listening devices that, by highlighting voices, help children hear better in noisy environments. With treatment, most children will be able to hear normally again.

Hearing aids are a kind of tiny amplifier. They help a person hear sounds better and can even pick them up, so that what children hear is clearer. Hearing aids send amplified sounds (through sound vibrations) from the hammer and middle ear to the inner ear or cochlea. Hearing aid technology is available that can adjust the volume of sounds automatically.

For some children who cannot hear or understand words even with the help of hearing aids, there is a device called a cochlear implant. It is a very tiny piece of electronic equipment that is placed in the cochlea during a surgical procedure. It does the work of damaged or destroyed hair cells in the cochlea by converting sounds into electrical signals that directly stimulate the hearing nerve.

Learning and communication

A child with hearing loss may attend a special school, take special classes at a regular school, or be in a regular class. Depending on the severity of their hearing loss, some children may work with audiologists or speech-language pathologists to develop their hearing and speech skills.

To communicate, some people with hearing loss may need to use special techniques such as the following:

  • speech reading, which involves looking closely at a person’s lips, facial expressions, and gestures to understand spoken words
  • American Sign Language (ASL), which uses hand movements to enable deaf people to communicate without speaking
  • word supplemented and English by exact signs, which use figures with the hands to translate what is being said; these techniques are meant to be used with spoken language to help people understand anything they cannot understand through lip-reading

What happens when you have to talk on the phone? Thanks to a telecommunication device (also called a TDD), you can have a conversation in writing, instead of speaking. The messages appear on a special screen or on a printed copy.

You may wonder how a person who can’t hear well can watch a movie or television. TV shows and subtitled movies include text at the bottom of the screen so that people with hearing loss can read and follow the action.