Otoacoustic emissions (OAE) testing refers to the measurement of sound emissions from the outer hair cells of the inner ear. OAEs can be used to specifically test the function of the cochlea (hearing cochlea).This examination is one of the objective tests of hearing ability.
Indications (areas of application)
- Hearing screening in newborns (first screening up to day 3).
- Early detection of intoxications affecting the ear; these occur primarily with cytostatic drugs
- Detection of hearing disorders
The procedure
In the measurement of otoacoustic emissions, the sound emissions of the hair cells of the inner ear are registered via a very sensitive microphone. The method is considered an objective examination method.
Different forms of OAE can be distinguished:
- Spontaneous otoacoustic emissions (SOAE); no specific acoustic stimulus is applied; this form can be performed in some individuals
- Forms in which an acoustic stimulus is delivered:
- Transitory evoked otoacoustic emissions (TEOAE) (used in newborn screening).
- Distortion-produced otoacoustic emissions (DPOAE).
- Simultaneous evoked otoacoustic emissions (SEOAE).
Measurement of otoacoustic emissions using TEOAE and DPOAE is considered a physiological (objective) hearing test.
Examination conditions (hearing screening in newborns):
- If possible, measure only from the 3rd day.
- During sleep
- No disturbing noises, no sucking
- Carefully insert the measuring probe into the ear canal, paying attention to the seal
Interpretation of hearing screening in newborns
- If otoacoustic emissions are present, it is safe to conclude that the middle and inner ear function is approximately normal.
- An abnormal measurement result does not always mean that the baby is hard of hearing.Causes of a “false positive” result may be fluid in the ear or clogged ear probes (cerumen/earwax).
In pathological OAE screening (abnormal measurement result) after repeat measurement: second stage with automatic BERA screening (ABERA; BERA: brainstem evoked response audiometry; acoustically evoked brainstem potentials; brainstem audiometry) as a second objective method of a hearing threshold determination.
The sensitivity of OAE screening (percentage of diseased patients in whom the disease is detected by the use of the test, i.e., a positive test result occurs) for middle and sensorineural hearing loss is reported to be 98 to 100%, while the specificity (probability that actually healthy individuals who do not suffer from the disease in question are also detected as healthy in the test) is reported to be 93.3 to 96.1%, depending on the device.
Otoacoustic emissions testing is a powerful diagnostic procedure in otolaryngology for early detection of hearing disorders.