Interacoustics Eclipse Additional Information page 59

Eclipse Additional Information
This method was originally formulated and tested by Elberling and Walhlgreen (1985). By comparing this
method of weighted averaging to traditional averaging and to different strategies for artifact rejection the su-
periority of weighted averaging was demonstrated by Don and Elberling (1994).
Measuring without Bayesian Weighting
Note how the residual noise gets worse when the contracted period starts. If the patient would have contin-
ued contraction for 10.000 sweeps we would start seeing the noise coming down of course, but it would
never reach the same low level as with Bayesian.
Measuring with Bayesian Weighting
Note how the residual noise still drops in the contracted situation, and never got worse.
Bayesian Weighting does not change the response of a waveform and Bayesian Weighting can be used in
all typical ABR recording situations.
Why use Bayesian?
 Optimum use of all data reduces in total the test time
 The recordings are more stable, as residual noise will never suddenly rise (and a good waveform deterio-
rate) during recording, even if patient starts to be uneasy.
 The difficulty of selecting the optimum rejection level is reduced, as a softer rejection rate can be used
without the noisier sweeps contaminating the more quite sweeps.
When is Bayesian Weighting less Relevant?
If the patient does not have a fluctuating EEG during the session: Bayesian weights noisy sweeps less and
quite sweeps more. In a situation where all sweeps are the same, they will be weighted equally. This is iden-
tical to normal averaging. Hence, there is no difference between recordings with and without Bayesian.
Page 49