Otoport OAE+ABR
User Manual for Otoport DP+TE model
131
Configuration
Stim Type
Stim type
sets the stimulus type used in the ABR test. The types available
are ‘click’ and ‘chirp’. See chapter
26
Mode of operation
for further details
of these stimulus types. The chirp stimulus has been demonstrated to
give a larger ABR response for the same stimulus level. Stim Type is
configurable only in ABRcustom, default is chirp in both modes.
Start
If
Start
is ON then the ABR test will proceed from the Impedance Check
screen to data collection (autostart) without any action from the tester if test
conditions are good.
If Start
is OFF the tester determines when to proceed from Impedance
Check to data collection (manual start).
Start is configurable only in ABRcustom, default is ON in both modes.
Stop
The
Stop
setting controls whether the test automatically stops when the
pass criteria are met. If
Stop
is turned OFF, the test will run for longer,
but the ABR levels will be more accurately measured. If
Stop
is ON when
screening, the test will be as short as possible.
Stop is configurable only in ABRcustom, default is ON in both modes.
Pass criteria
Pass criteria
sets the conditions in which the ABR test will give a pass
result.
Pass criteria
is based on a statistical measure similar to signal to noise
ratio known as Fsp, and a measure of the extent to which the averaged
response waveform resembles a typical neonate ABR, a value referred to
as template correlation (TC).
Fsp is the principle determinant of a Pass. It must achieve a minimum
fixed Fsp
or
dynamic Fsp
level. The
dynamic Fsp
threshold rises if
power line noise is a large part of the electrical noise measured in order
to account for any possible contribution of the powerline noise to Fsp
(to ensure that the powerline noise is not mistaken for an ABR). The
minimum
fixed Fsp
threshold is higher than the largest Fsp ever likely to be
achieved by chance in EEG noise.
The
minimum TC
requirement should be achieved when recording an ABR
waveform from a neonate (34 weeks to 6 months gestational age). The
strict TC
requirement is higher than largest TC ever likely to be achieved by
power line interference.