In Poland since 2002 otoacoustic emission (OAE) is a screening hearing exam. Every newborn starting on the second day of life is screened on the neonatal unit close to hospital discharge and/or when they are medically stable. Otoacoustic emissions is a response of cochlear auditory cells to tonal pulse or cracks provided by the probe.
OTOACOUSTIC EMISSION OCCURS IN ALL GOOD HEARING, ALSO IN NEWBORNS
Indications for testing:
– assessment of the inner ear, – hearing screening for infants, – topodiagnostic assessment of hearing loss, – monitoring changes in hearing after taking ototoxic medications, – detection of functional deafness, – tinnitus diagnostics.
What is otoacoustic emission performed for?
Otoacoustic emissions (OAE) is a non-invasive, objective and easy method of assessing the activity of the cochlea. It involves recording responses in frequencies other than the frequency of the administered stimulus. Aside from using OAE in screening newborns, it has found its rightful place in the set of topodiagnostic tests of hearing disorders. The credibility of OAE test depends on the limitations of the method and the measurement conditions. One of them is the correct aeration of the middle ear, and impaired conduction system ensuring the sound will reach the inner ear. Pressure disturbance in the tympanic cavity and in the external auditory canal may affect the response parameters of OAE.
How is the OAE performed??
The test involves placing a probe in the ear canal. The probe consists of a small speaker that emits sounds and a small, highly sensitive microphone recording otoacoustic emission. When the stimulus sound coming from the speaker moves the hair cells, which produce secondary sound picked up by the microphone. OAE test should be carried out in a soundproof room. The test is completely non-invasive but requires low mobility of the child during the examination, as well as special acoustic conditions (silent room or cubicle).
Otoacoustic emission in children:
If during the test, there was no OAE, it does not necessarily mean hearing loss. There may be several reasons for the lack of OAE. The examination was carried out in a room that was not soundproofed enough. In newborns, especially during the first three days of life, the placental membrane or amniotic fluid may clog the ear canal and cause a negative OAE test result. Otitis media or ordinary cold can also cause temporary disruptions in the sound conduction. The presence of OAE confirms that the hair cells are working properly. Nevertheless, the occurrence of OAE does not indicate that a further part of the auditory system (vestibulocochlear nerve and areas of the brain responsible for hearing) is functioning properly.
Materials from the Siemens Audiology: https://www.bestsound-technology.pl/children/testing-children/objective-audiometry/
Author: Aleksandra Stojak