Masking - Interacoustics Affinity 2.0 Additional Information

Test procedure:
1) Open the AC440 module through Noah or OtoAccess®.
2) If needed select a test protocol in the List of Protocols.
3) Prior to bone conduction audiometry, perf orm the Air conduction audiometry, as described in section
0.
4) Place the bone conductor on the mastoid of the worst ear and choose Bone Right or Bone Left f rom
the channel 1 output dropdown list and select the desired test signal (typically Tone). In the channel
2 input and output dropdown lists you can decide whether masking is to be employed. If so, you will
need to place the headset on the patient as well.
Conduct high f requency audiometry using the normal air conduction audiometry method (see section 0
above f or details).
Note: Without appropriate masking applied where necessary you cannot know which cochlea is responding,
as there is always no interaural attenuation in bone conduction audiometry. We will always assume that it is
the better ear that is responding. In the case of asymmetrical hearing losses, bone conduction masking
should always be considered.
1.7.4

Masking

In cases where a symmetrical hearing loss is detected, traditional audiometry without masking is usually
suf f icient. However, be aware that in cases of asymmetrical hearing loss, one cannot be certain that the test
ear is the one 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 suf ficient magnitude. Theref ore, you are measuring the thresholds f rom 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 f requency it can, on average be estimated to a minimum of 40 dB f or supra-
aural headphones and 55 dB f or 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 Af f inity hardware
•
• Licensed AC440 Audiometry module within your Af f inity
• 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®.
Select a test protocol in the list of Protocols and sessions if needed.
2)
3) Perf orm the Air conduction audiometry as described in section 1.6. If the dif f erence between lef t and
right air conduction thresholds at any f requency are 40 dB (headphones) or 55 dB (inserts) and higher
then masking is required.
4) Perf orm Bone conduction audiometry as described in section 1.6.3
5) If the dif f erence between the air conduction threshold of the worse ear and the bone conduction
threshold of the better ear exceeds 10 dB, masking is needed.
D-0004576-Q – 2022/05
Affinity/Equinox2.0 – Additional Information
2.0 hardware
audiometry. The
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