Correction of blink artifacts from single channel EEG by EMD-IMF thresholding

摘要

Electroencephalogram (EEG) is bioelectric signal, which represents the brain activity and usually contaminated with artifacts due to movements of eye, heart, muscles and power line interference. Among these, artifacts due to Ocular Activity make the analysis difficult. This paper presents a new threshold for the removal of Ocular Artifacts (OA) from single channel EEG based on Empirical Mode Decomposition (EMD) inspired by Wavelet Thresholding that yields a relatively cleaner EEG signals. Unlike the conventional EMD based EEG denoising techniques, that neglects the higher order low frequency Intrinsic Mode Functions (IMFs) EMD Interval Thresholding (EMD-IT) and Iterative EMD Interval Thresholding (EMD-IIT) is opted to correct the artifacts. Computations are carried out using EEG Motor Movement/Imagery (eegmmidb) dataset and compare the performance of Proposed Threshold (PT) with current threshold functions i.e., Universal Threshold (UT) and Statistical Threshold (ST) using several standard performance metrics: Change in SNR (ΔSNR), Artifact Rejection Ratio (ARR), Correlation Coefficient (CC) and Root Mean Square Error (RMSE). Results of these studies reveal that the EMD-IT with PT can effectively remove the OAs from EEG signals and maintaining the background neural activity in non artifact zones intact in contrast with those of existing ones.