Two-dimensional spectral processing of sequential evoked potentials

The processing of sequential evoked potentials (EPs) is investigated using two-dimensional processing techniques. Two-dimensional EP arrays or images are formed by stacking sequential recordings. Processing is accomplished in the frequency domain by 2-D low-pass filtering using Gaussian filters. Auditory brainstem responses (ABRs), which are the early auditory EPs, are used to investigate the effects of the 2-D filtering on real data. Gaussian filtering improves signal-to-noise ratios by reducing high frequency noise effectively in both intra-EP and inter-EP dimensions. Applications to intra-operative monitoring are simulated with real ABR data.