OAE screening takes place as standard practice now in the UK as well other countries across the world and is an effective tool to avoid delay in the detection of hearing loss in children. But how does the test work, and what does it really mean for your child?
When we hear a sound, the outer hair cells in the ear vibrate and stimulate the inner ear (cochlea). This vibration causes an echo into the middle ear that is almost audible. If hearing loss is present in a child (or adult for that matter), these soft emissions will not occur. When newborns hearing is tested with an OAE (oto-acoustic emissions) test, a small probe is inserted into the child’s ear canal to measure for this sound.
The OAE screening programme was introduced to prevent deaf children with no family history or significant risk factors of hearing loss from ‘slipping through the net.’ This is important because children’s hearing loss can have a huge impact on language development if not detected and treated at an early age.
During an OAE test, a small microphone is inserted into the child’s ear and a clicking sound is played. If the cochlea is functioning as it should, this clicking sound will echo back into the ear piece. The results of the test are recorded onto a computer. If the results indicate a strong echo, no further tests will be done, but if the results indicate weak responses, the child will be referred for further tests. The OAE test can be performed very quickly, and without any upset to a newborn.
A fail on an OAE test at birth does not necessarily indicate hearing loss as other factors can affect the test results, such as fluid in the ears from the birthing process (more common in caesarean birth), a noisy room or simply a fidgety baby. The OAE test can detect blockages, middle ear fluid and outer hair cell damage as they are designed specifically to identify impaired cochlea function. With this in mind, an OAE test may not only pick up permanent hearing losses but can also be valuable in detecting other issues such as middle ear infections (otitis media), wax build-up or glue ear. Usually, the next step after a fail on an OAE hearing test will be another OAE, before moving on to an ABR (auditory brainstem response) test.
Currently in the UK, around 15% of newborns will be referred for an ABR screening test, and roughly 0.1-0.3% of children born each year in the UK are diagnosed with a permanent hearing loss, showing that conductive hearing issues can play a large part in OAE screening failure.