otometrics Madsen Xeta, Reference Manual

Page: 49 / 108

5.2.6 Preparing for testing with masking
See Air conduction with masking - suggested procedure
►
72 for a recommended procedure on testing with masking.
When to use masking for Air Conduction testing
If the difference between the thresholds in the two ears is 40 dB or greater, it is recommended that you test the poorer
ear again with masking applied to the better ear. See
Testing with masking ► 72 .
If the appliance of masking is to be optimally administered without using unnecessary masking, it is recommended in the
literature not to use the one-number-fits-all 40 dB criterion for circum-aural and 55 to 60 dB criterion for insert phones.
This may cause errors, and will increase the test time, as well as increase the strain on the patient. Instead, the literature
recommends the use of frequency specific criteria that would be taken from transducer specific inter-aural attenuation
tables available from clinical studies.
1
Use the Masking Assistant for easy application of this method.
When to use masking for Bone Conduction testing
If the difference between the air conducted threshold and the unmasked bone conduction threshold of the same ear is
15 dB or greater, it is recommended that you retest bone conduction thresholds with masking applied to the contralateral
ear. See
Testing with masking ► 72 .
When to use a mono insert phone
Masking via insert phone is recommended. The mono insert phone gives less inter-aural cross talk than the TDH39 head-
phones.
The test procedure is similar to that described in Bone conduction with masking - suggested procedure
►
73 .
Instructing the patient
• In addition to the tones in the test ear, the patient will be hearing a noise in the other ear.
• The tones can be heard in either ear.
• The patient should respond to the tones in the test ear and ignore the noise.
• The patient should press the patient responder as soon as the tone is heard.
• You may prefer that the patient raises a hand to indicate in which ear the tone was heard. This is particularly relevant
since masked testing is used to determine that the signal is perceived by the test ear.
5.3 Listening check
Perform listening checks routinely to make sure that the equipment is functioning properly.
• Use a person who has auditory thresholds below 10 dB and make sure that he or she can hear a very faint sound for
each stimulus type, frequency and for each transducer at 0 to 5 dB.
• If the person cannot hear the stimulus, contact the manufacturer or local representative to troubleshoot the system.
• It is recommended that the system be calibrated annually or according to the local requirements.
1(Katz, J., Lezynski, J. (2002). Clinical Masking. In J. Katz, ed.,
Handbook of Clinical Audiology
, Williams and Wilkins, Bal-
timore.)
Otometrics - MADSEN Xeta 49
5 Preparing for testing