1.5.4 Acoustic Reflex Decay (MI 36 Version Only)
Acoustic reflex decay, also known as adaptation, is the measurement of the acoustic
reflex response during sustained stimulus presentation. Ipsilateral and Contralateral
Reflex Decay can be performed.
1.5.5 Eustachian Tube Dysfunction (ETF) (MI 36 Version Only)
The Eustachian tube connects the middle ear with the nasopharynx. Its function is to
equalize pressure between the middle ear and the atmosphere.
The Eustachian tube test can be used to determine if the Eustachian tube is functioning
properly in patients.
• ETF Intact: performed on patients with normal tympanic membrane (TM).
• ETF Perforated: determines if the patient can open his/her Eustachian tube when
the TM is perforated or an open PE-tube is in place.
1.5.6 Air Conduction Testing
Hearing threshold levels can be determined by presenting test signals to the test
subject with the included headphones (Air Conduction – AC). The purpose of AC
audiometry is to establish the hearing sensitivity at various frequencies. The test can
specify the AC loss but cannot distinguish between a conductive versus a
sensorineural abnormality.
1.5.7 Bone Conduction Testing (MI 26 Version – Extra License, MI 36 Version – Included)
Hearing threshold levels can be determined by presenting test signals to the test
subject with the included bone conductor (Bone Conduction – BC). The purpose of
BC audiometry is to establish the hearing sensitivity at various frequencies. The test
can specify the BC loss in combination with AC loss it can distinguish between
conductive versus a sensorineural abnormality.
1.5.8 Masking (MI 26 Version – Extra Bone Conduction License, MI 36 Version – Included)
Masking is required if there is a notable threshold difference between the left and right
ears. It is possible for sound to be transmitted to both ears via bone conduction while
testing the poorer ear. This is called “crossover”.
Crossover occurs often while testing bone conduction, but it can also occur during air
conduction testing. Relevant to crossover is the sound level received by the opposite
ear. The difference between the original test signal in the test ear and the received
signal in the opposite ear is called “interaural attenuation”.
For Bone Conduction measurements the interaural attenuation is 0 dB to 15 dB.
Bone Conduction crossover is therefore possible even with a slight difference in
hearing loss between ears.
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