Eclipse Additional Information Page 47
The scale for the residual noise goes from 0nV to 200nV in the combined Fmp & residual noise view. Typi-
cally a residual noise level of 40nV is considered by some as a practical noise target for no-response situa-
tions. Lower residual noise figures (ideally 20nV or less) increase the confidence that a response is truly ab-
sent rather than being obscured by residual noise.
Fmp range
The Standard Fmp range is calculated by using a 10ms range.
By selecting Manual the Fmp 10 ms range can be modified to the desirable range for a particular test. It is
normal to place the Fmp confidence detector on the timeline where the response is expected, similar to the
older waveform reproducibility.
3.7.1.8 Recording begin and end
If you want the recording to start e.g. 2ms prior to the stimulus onset, select -2ms in the bar. Similarly, you
may delay the onset of data acquisition until maximum 2ms after the stimulus onset. Please note that the
time window of ABR-15 recording is always 15ms for normal ABR, so if the recording is started prior to stim-
ulus onset, then the recording will not quite extend to the 15ms point on the time axis. For threshold testing,
especially with tone bursts at lower frequencies, longer latencies are recorded. Setting the recording to begin
at +2ms has the effect of extending the recording window to 17ms after the stimulus thus aiding in the identi-
fication of near-threshold responses.
ABR-30 will provide a 30ms recording window for test routines where 15ms recording window is considered
inappropriate.
3.7.1.9 Rejection
Select the default rejection level for the test protocol. A low rejection e.g. ±20µV level should be used. This
will allow only recordings containing a minimum of amplitude (less noise) to be recorded.
When a rejection level is chosen the gain is also set. When either or both EEG tracings is/are shown with
red, it is indicating full rejection and no recordings are created.
Click Advanced to enter more rejection level settings to specify in which time range normal rejection is ap-
plied. By doing this a potential artefact e.g. stimuli, causing the entire sweep to reject, can be avoided.
Simply grab the vertical lines with the mouse and move them along the time axis.
Notice the Rejection disabled areas cannot exceed the Fmp range as this is used for the Fmp and Residual
noise calculation. If you need to adjust the window further, the Fmp range must be moved prior to.
Notice if the grey areas turn red, the recording circuits have been overloaded and to safeguard incorrect re-
cordings all sweeps are rejected. Should you choose to overrule the protection, check the box Disable re-
jection (for eABR only).
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