Check out this blog from Adam Walker (Audiological Scientist) at Spire Manchester Hospital & Manchester Children’s ENT Clinic:

What is an Otoacoustic Emission (OAE)?

An OAE is essentially a measure of the function of the outer hair cells in the cochlea.  There are two methods of eliciting an OAE:

Transient Evoked OAEs (TEOAE)

TEOAEs are recorded by playing a broadband click stimulus at a level of around 80dB peSPL into the ear via a probe and recording an ‘echo’ from the cochlea if the sound is detected.  TEOAEs provide a broad assessment of the ability of the cochlea to detect sound. They give an indication that the cochlea is working reasonably well and are very useful in babies, or to confirm the findings of a hearing test. TEOAEs are used in the UK Newborn Hearing Screening Protocol (NHSP) to broadly assess cochlear function in newborns.

Distortion Product OAEs (DPOAE)

DPOAEs are recorded in the same way as TEOAEs but using a different stimulus. In TEOAEs 2 frequency specific stimuli are presented to the cochlea, with the ‘combination’ of these two frequencies creating a ‘distortion product’ at another specific frequency within the cochlea.  We are then able to record the ‘echo’ from that particular frequency in the cochlea. Therefore, DPOAEs are more ‘frequency specific’ than TEOAEs.

The measurement of OAEs is heavily dependent on good middle ear function (i.e. no glue ear/OME).

 

What is an Auditory Brainstem Response (ABR)?

An ABR is an electrophysiological measurement of the auditory response at the brainstem.  This test can be automated (aABR), as used in the UK NHSP, or can be ‘diagnostic’ whereby the audiologist can control parameters such as sound frequency and stimulus level.  In an ABR, a frequency specific tone burst is played via headphones or a bone conductor,  with recording electrodes  (forehead and behind each ear) positioned to record the neurological response to the sound at the level of the brainstem.  This test is an accurate and reliable method of assessing hearing in children too young for, or not developmentally ready for, behavioural testing, but needs to be performed with the child in natural sleep, sedated or under GA.