A new technique for removal of ocular artifacts from EEG signals using S-transform

Abstract

A novel and robust technique is described for removing electroencephalogram (EEG) artifacts resulting from ocular muscles contraction during eye movements. We present a new method to remove ocular artifacts from raw EEG signals. This technique is based on the S-transform (ST), a mathematical operation that produces frequency content at each time point within a time-varying signal. The S-transform generates high magnitude S-coefficients at the instants of artifact generation in the signal. A statistical threshold function has been applied to filter out the artifacts in the S-domain. The major advantage of ST-filtering is that the artifacts may be removed within a narrow time frame, while preserving the frequency information at all other time points. It also preserves the absolutely referenced phase information of the signal after removing the artifacts.