Question

Otoacoustic Emissions (OAE).

Hint:

Otoacoustic emissions are highly effective in detecting early cochlear dysfunction, making them an essential part of newborn hearing screening programs.

Answer 1

Step 1: Definition of Otoacoustic Emissions (OAE).
Otoacoustic Emissions (OAEs) are sounds generated by the cochlea in response to an external stimulus. These emissions are a by-product of the mechanical activity of the outer hair cells in the cochlea. When the cochlea is functioning properly, these cells generate sounds that travel back through the middle ear to the ear canal, where they can be detected with a microphone. OAEs are used to assess cochlear function, especially the integrity of the outer hair cells, which are critical for hearing.

Step 2: Types of Otoacoustic Emissions.
There are two main types of otoacoustic emissions:
- Spontaneous OAEs: These emissions occur without any external stimulus, and they are present in the ear canal in some individuals.
- Evoked OAEs: These emissions are generated in response to an external sound stimulus. There are two types:
- Transient Evoked OAEs (TEOAEs): These are evoked by brief stimuli, such as clicks or tone bursts.
- Distortion Product OAEs (DPOAEs): These are evoked by presenting two tones of different frequencies, which create a third frequency (the distortion product) that can be detected in the ear canal.

Step 3: Clinical Use of OAE.
OAEs are commonly used in clinical audiology for:
- Newborn hearing screening: OAEs are used as a quick and non-invasive method to test hearing in newborns.
- Monitoring cochlear function: OAEs can detect early signs of cochlear damage, especially in individuals at risk for hearing loss, such as those exposed to loud noise or ototoxic drugs.
- Diagnosis of hearing loss: OAEs help differentiate between sensorineural and conductive hearing loss. If OAEs are absent but the auditory nerve is intact, it suggests a cochlear problem rather than a nerve problem.

Step 4: Conclusion.
Otoacoustic emissions are a valuable tool in assessing cochlear function, especially the outer hair cells. They are useful for screening, diagnosing, and monitoring hearing loss, particularly in newborns and individuals at risk.