Evaluation of the Wiener filter applied to evoked EMG potentials

The application of the Wiener filter to the estimation of responses evoked in the tonic EMG activity of tibialis anterior by cutaneous electrical stimulation of the foot is described. The effectiveness of the filter is assessed using both experimental and simulated data by computing the mean square error between the actual evoked potential and ensemble average and Wiener filter estimates of it. The Wiener filter is shown to provide a better estimate of the final response than simple ensemble averaging. The improvement is most marked in cases where the signal-to-noise ratio is small, but the Wiener filter estimate is always better than the ensemble average estimate. It is concluded that Wiener filtering significantly reduces the number of responses required to obtain a good estimate of the evoked potential in this experimental situation.