Causes of hearing problems
Some possible causes of hearing loss that may be detected during routine tests include:
- Glue ear – a build-up of fluid in the middle ear, which is common in young children
- Infections that develop in the womb or at birth, such as rubella or cytomegalovirus, which can cause progressive hearing loss
- Inherited conditions, such as otosclerosis, which stop the ears or nerves from working properly
- Damage to the cochlear or auditory nerves (which transmit hearing signals to the brain); this could be caused by a severe head injury, exposure to loud noise or head surgery, for example
- Being starved of oxygen at birth (birth asphyxia)
- Illnesses such as meningitis and encephalitis (which both involve swelling in the brain)
Spotting signs of a hearing problem
In older children, signs of a possible hearing problem can include:
- Inattentiveness or poor concentration
- Not responding when their name is called
- Talking loudly and listening to the television at a high volume
- Difficulty pinpointing where a sound is coming from
- Mispronouncing words
- A change in their progress at school
Hearing tests for children
Some of the main tests carried out are described below:
Visual reinforcement audiometry
Visual reinforcement audiometry (VRA) is usually used to test hearing in children from approximately seven months of age up to two-and-a-half years old.
During the test, your child will sit on your lap or a chair while sounds are presented. Your baby will be taught to link the sound to a visual reward such as a toy or computer screen lighting up.
Once your child is able to associate the sound and the visual reward the volume and pitch of the sound will be varied to determine the quietest sounds your child is able to hear.
Play audiometry
Young children between two and five years old may have a play audiometry test.
During the test, sounds will be played through headphones or speakers and your child will be asked to perform a simple task when they hear the sound. This may vary from putting a ball in a bucket to completing a puzzle.
As with VRA, the volume and pitch of the sound will be varied to determine the quietest sounds your child is able to hear.
Pure tone audiometry
Older children may have a test called pure tone audiometry. This is the test often used to screen a child's hearing before they start school, when it is sometimes referred to as the "sweep test". It's similar to a hearing test an adult might have.
During pure tone audiometry, a machine generates sounds at different volumes and frequencies. The sounds are played through headphones and your child is asked to respond when they hear them by pressing a button.
By changing the level of the sound, the tester can work out the quietest sounds your child can hear.
Bone conduction test
In addition to using speakers or headphones, most of the tests above can also be carried out using a small vibrating device placed behind the ear.
This device passes sound directly to the inner ear through the bones in the head, which can help identify which part of the ear isn't working properly if your child is having hearing problems.
Speech perception test
This can be performed in a variety of ways depending on your child's age and ability. Some may be performed using voice and others may involve playing speech through headphones or a speaker. The child may need to identify words they hear by pointing at a toy, picture, or repeating what they hear.
Tympanometry
Tympanometry is a test to assess how flexible the eardrum is.
For good hearing, your eardrum needs to be flexible to allow sound to pass through it. If the eardrum is too rigid – for example, because there is fluid behind it (glue ear) – sounds will bounce back off the eardrum instead of passing through it.
During the test, a soft rubber tube will be placed at the entrance of your child's ear. Air is gently blown down the tube and a sound is played through a small speaker inside it. The tube then measures the sound that's bounced back from the ear.