Optimal ('Wiener') digital filtering of auditory evoked potentials: use of coherence estimates.

Auditory evoked potentials (AEPs) to 40 Hz clicks and amplitude-modulated 500 Hz tones in human subjects were digitally filtered using an optimal ('Wiener') filter uniquely determined for each AEP. Use of coherence functions to compute coefficients appropriate for filtering grand average AEPs or subsets such as split-half averages is described. Wiener-filtered AEPs correlated better than unfiltered AEPs with split-half replicates and with reference AEPs (obtained with long data collection periods). Visual detection thresholds were lower (more sensitive) for the Wiener-filtered AEPs, but not as low as objectively determined thresholds using coherence values.