Recording Properties - Interacoustics Eclipse Additional Information

Eclipse Additional Information Page 46
The Gain info on raw EEG allows you to change the display of the EEG window; off, in dB, and as a factor
are the options.

3.7.1.7 Recording properties

Stop criteria
Allows you to select the maximum number of accepted stimuli you
need for each test. You can extend the maximum of sweeps on the re-
cording screen.
A typical number of stimuli (sweeps) are
4000. Note the stop criteria should be based on statistical parameters
and a clinical evaluation of the collected curve rather than a defined
number of sweeps.
Response confidence
The Response Confidence drop down lets you change the Response
confidence setting to off, 99%, 97.5% or 95%. Default is 99%, which
provides the most accurate measure.
The selected criteria can be set as Stop Criteria by ticking the box.
The ABR software calculates the signal-to-noise ratio (SNR) of the av-
eraged ABR waveform. The Response Confidence is based on the
principles described in detail by Elberling and Don (1984 & 2006), and
Don and Elberling (1994 & 1996), and is called Fmp. During the re-
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cording of the ABR, the actual value of the Fmp (~ SNR ), and a graph
showing how the response confidence develops along with the data
collection (number of sweeps), is presented on the screen.
An Fmp value higher than 3.1 indicates with 99% accuracy that a re-
peated response is present in the recorded waveform. In this way Fmp
can be used for objective detection of repeated waveforms.
A minimum of 800 sweeps must be recorded before the Fmp value is
used as a stop criteria and ends the test (in order to retrieve sufficient mathematic data).
Residual noise
The Residual Noise Target Line dropdown lets you change the setting for the residual noise target line and
allows you to set the residual noise level as Stop Criteria by ticking the box. When the box is ticked the test
will stop automatically when the set criterion for residual noise is reached.
The residual EEG-noise in the averaged ABR waveform is calculated. The residual noise calculation is
based on the principles described in detail by Elberling and Don (1984 & 2006), and Don and Elberling (1994
& 1996). A Residual noise value of 40nV or less indicates that the waveform contains a minimal amount of
noise and the recording can be stopped. Therefore if a response is present it is not due to noise in the re-
cording. If a response is absent with a low residual noise value, it can be concluded that there is no repeated
response in the actual recording, hence averaging can be stopped.
A minimum of 800 sweeps must be recorded before the residual noise value is used as a stop criteria and
ends the test (in order to retrieve sufficient mathematic data).