A baseline hearing test is routinely done before chemotherapy begins, and repeated periodically.
Some chemotherapy drugs used for retinoblastoma can cause hearing loss. Regular hearing tests detect small changes early.
Depending on your child’s age, the test will be either an audiogram Otoacoustic Emissions test or Auditory Brainstem Response test.
Your child will sit in a soundproof room to remove all ambient noise during the test. You should be allowed to stay with your child during this test, but you will be asked to remain silent throughout so your child is not distracted.
Earphones will be placed over both ears, through which sounds, such as beeps and tones, are played. Your child will be asked to press a button, raise a hand or say “yes” in response to each sound heard. The test is repeated for each ear. The results of the audiogram are usually displayed on a graph.
Otoacoustic Emmissions (OAE)
This test is used for infants and very young children.. Unlike the audiogram, your child is not required to do anything, but she must remain as still and quiet as possible to obtain an accurate measurement.
Otoacoustic emissions are faint acoustical signals emitted from hair cells in the cochlea (inner ear), in response to stimuli.
A soft pillow-like plug will be placed at the opening of your child’s ear canal. The plug contains two speakers through which various tones are played, and a mic to record the otoacoustic emissions they generate.
Auditory Brainstem Response (ABR)
This test is used for infants and very young children.. Like the Otoacoustic Emissions test, it does not require your child to do anything.
Sound travels through the outer ear as vibrations, and converted to electrical signals by the cochlea. Signals travel along the auditory nerve to the brain, which interprets them into sounds that we can understand.
The ABR test records brain activity in response to sounds. Headphones will be placed over your baby’s ears, through which a series of clicking sounds is played. Three small sensors are attached to the baby’s head and connected to a computer.
The computer records brainwave response to the different sounds. The results are usually documented on a graph.