Author(s)

Kedarnath Senapati, Aurobinda Routray

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Ocular artifacts are most unwanted disturbance in electroencephalograph (EEG) signals. These are characterized by high amplitude but have overlap-ping frequency band with the useful signal. Hence, it is difficult to remove the ocular artifacts by traditional filtering methods. This paper proposes a new approach of artifact removal using S-transform (ST). It provides an instantaneous time-frequency repre-sentation of a time-varying signal and generates high magnitude S-coefficients at the instances of abrupt changes in the signal. A threshold function has been defined in S-domain to detect the artifact zone in the signal. The artifact has been attenuated by a suitable multiplying factor. The major advantage of ST-fil- tering is that the artifacts may be removed within a narrow time-window, while preserving the frequency information at all other time points. It also preserves the absolutely referenced phase information of the signal after the removal of artifacts. Finally, a com-parative study with wavelet transform (WT) and in-dependent component analysis (ICA) demonstrates the effectiveness of the proposed approach.

EEG, Ocular Artifact, S-transform, Wavelet Transform, Independent Component Analysis

Senapati, K. and Routray, A. (2011) Comparison of ICA and WT with S-transform based method for removal of ocular artifact from EEG signals. Journal of Biomedical Science and Engineering, 4, 341-351. doi: 10.4236/jbise.2011.45043.