Masking - Interacoustics Affinity 2.0 Additional Information

2.0
Affinity Additional Information
1.7.4

Masking

In cases where a symmetrical hearing loss is detected, traditional audiometry without masking is usually
sufficient. However, be aware that in cases of asymmetrical hearing loss, one cannot be certain that the test
ear is the one actually detecting the sound. For example, when measuring an audiogram on a patient with
hearing within the normal range on one ear but a moderate to severe hearing loss on the other, there is a
potential risk that the better ear is the one responding, even if it is not the ear being tested. That is because
the sound vibration may travel through the head and be heard by the opposite ear when the vibrations of the
signal are of sufficient magnitude. Therefore, you are actually measuring the thresholds from the wrong ear.
To prevent this phenomenon in causing an erroneous measurement, masking noise can be used to occupy
the better ear (non-test ear) while testing the other one (Stach 1998, Katz 2002 and British Society of
Audiology 2004). Masking can be applied to air conduction, bone conduction and speech
need to mask the better hearing ear is linked to the interaural attenuation which equals the amount of
attenuation the sound is exposed to on its way through the skull. Even though the interaural attenuation is
very individual and varies with frequency it can, on average be estimated to a minimum of 40 dB for supra-
aural headphones and 55 dB for inserts. Regarding bone conduction, the interaural attenuation is a minimum
of 0 dB which means that crossing over of the stimulus may occur all the time.
Required Items:
•
The Affinity hardware
•
Licensed AC440 Audiometry module within your Affinity
•
Calibrated Headphones or insert phones
•
A calibrated bone conductor (B81)
•
A patient response button
Test Procedure:
1) Open the AC440 module through Noah or OtoAccess™.
2) Select a test protocol in the list of Protocols and sessions if needed.
3) Perform the Air conduction audiometry as described in section 1.6.
4) Perform Bone conduction audiometry as described in section 1.6.3
5) If the difference between the air conduction threshold of the worse ear and the bone conduction
threshold of the better ear exceeds 10 dB, masking is needed.
2.0
hardware
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audiometry. The