Otoacoustic Emissions (OAE), also known by their English acronym OAE (Otoacoustic Emissions), are one of the audiological diagnostic tests available.
They are sounds emitted by the cochlea as a result of the activity of the hair cells in the organ of Corti. These sounds travel outward through the middle ear and can be detected in the external auditory canal.
Types of Otoacoustic Emissions:
Spontaneous Otoacoustic Emissions (SOAE)
These are OAEs that occur in the absence of any external stimulus. They are recorded in only about 50% of ears with normal hearing and at limited frequencies, so their clinical usefulness is restricted.
Evoked Otoacoustic Emissions (EOAE)
These are OAEs generated in response to an acoustic stimulus and can be recorded in most normal ears. Depending on the characteristics of the stimulus, different types of EOAE can be obtained:
- Transient Evoked Otoacoustic Emissions (TEOAE)
Produced by a brief stimulus (click, tone burst, etc.). They are indicated for detecting cochlear lesions and are especially useful for the early diagnosis of hearing loss. - Stimulus-Frequency Otoacoustic Emissions (SFOAE)
Produced by a continuous frequency stimulus. Their detection is more complex and time-consuming; therefore, they are not commonly used in clinical practice. - Distortion Product Otoacoustic Emissions (DPOAE)
Generated by stimulating the ear with two pure tones simultaneously, resulting in the emission of a third tone at a frequency different from the original stimuli. These have great clinical value because they allow frequency-specific assessment and early detection of mild cochlear damage that may not be visible with conventional audiometry.
These tests are quick, simple, and completely non-invasive. For the recording, it is only necessary to place an insert earphone adapted to the patient’s age and the size of their external auditory canal.
The results obtained are objective, as they do not require the patient’s active participation.
Main Clinical Applications of Otoacoustic Emissions:
- Hearing screening or early detection of deafness in newborns.
- Identification of hearing loss in non-cooperative patients (young children, individuals with intellectual disabilities, malingerers, etc.).
- Early detection and prevention of hearing damage in individuals exposed to noise.
- Monitoring of hearing damage caused by ototoxic medications.