Otoacoustic emissions (OAE)’s are low-level sounds generated by the outer hair cells of the cochlea (inner ear) in response to auditory stimuli. OAEs are present in nearly all normal-hearing ears. Absent OAEs indicate hearing loss and/or middle ear pathology.
When are OAE tests used?
OAE tests are used to assess the following:
Infants over 90 days old and children up to 4 years of age
Children and adults who are or who are unable to cooperate with other methods of Hearing testing (e.g. individuals with autism or stroke)
Children with developmental or delayed speech or language disorders
Individuals with tinnitus, acoustic trauma, noise induced hearing loss, or sudden hearing loss
Individuals with abnormal auditory perception
Individuals with sensorineural hearing loss
Individuals with abnormal auditory function studies or failed hearing exam
Potentially malingering individuals who may be faking a hearing loss
Monitoring of ototoxicity in patients before, during, and after administration of agents known to be ototoxic (damaging to the hearing and/or balance systems)
What will happen during the test?
An OAE probe with eartip is inserted into the ear canal to obtain a seal. The acoustic signal is presented from the probe. The signal travels through the ear canal, the middle ear, and finally reaches the cochlea where the outer hair cells are excited and the emission is generated. The emission travels back through the middle and outer ears and is detected by a highly sensitive microphone in the OAE probe. Other than the annoyance of having a soft plug in your ear canal, the patient will not experience any discomfort. Newborns will often sleep during the entire procedure. The testing will take approximately 30 minutes from start to finish.
Types of OAE’s
Distortion Product Otoacoustic Emissions (DPOAEs) DPOAEs are generated by simultaneous stimulation of the outer hair cells by presenting two pure tones of different frequency through the OAE probe.
Transient Evoked Otoacoustic Emissions (TEOAEs). TEOAEs are generated when the ear is stimulated by clicks or tonebursts.
DPOAEs and TEOAEs are equally reliable in the 1.5 kHz to 4 kHz range. TEOAEs are more reliable for frequencies below 1.5 kHz while DPOAEs are more reliable for frequencies above 4 kHz.