CHAPTER SEVEN
ABR test procedure
50
ABR test procedure
7.4.4
Stimulus monitoring
At intervals during the testing the acoustic stimulus and noise levels are
checked. If the stimulus level has changed the ‘Check Probe Fit’ message
is shown. If the environment has become too noisy to test the ‘Noisy’
message is shown. In either case data collection is suspended until
stimulus and noise levels are within range again. The Otocheck will beep
to warn the user of test conditions if either ‘Check Probe Fit’ or ‘Noisy’
conditions persist.
If the ‘Check probe fit’ message is shown, it is most likely because the
probe has fallen out of the ear. Adjust the probe fit until the message goes
away; data collection will automatically restart.
7.4.5
Pausing the test
Select
Pause
to temporarily stop data collection. You may wish to do
this if the test environment worsens (for example the subject becomes
temporarily active, an electrode becomes detached or the probe falls out of
the ear). If a test is paused an impedance check is automatically run and
electrical noise is monitored (as in section
7.1
).
Failure to measure discernible ABR data within the defined test time, and
within acceptable NLO range or before ABR noise target is reached, will
return a
No Valid ABR
result.
7.4.6
Test stop reasons
There are five possible ways in which a test can stop, described below.
When the test stops the data collected is assessed. The result is given as
a pop-up graphic and written highlighted at the top of the test screen. The
Otocheck will beep once if a test has stopped with an ABR Pass result and
will beep twice if the test has stopped with any other result.