**1.5 De-noising EEG signals**

During the recording process, there is always a possibility of occurrence of contamination in EEG data at multiple points. Over which most of the artifacts that occurred here belong biologically generated by sources and are external to the brain. By significant improvement in existing technology, these externally generated artifacts could be removed, thus it is important to study efficient de-noising (a process for noise removal) procedures that would be able to remove these biological overlays from EEG signals. Actual EEG recordings are the summation of artifacts with the pure EEG signal, and can be defined mathematically:

$$E\left(t\right) = \mathcal{S}\left(t\right) + \mathcal{N}\left(t\right) \tag{5}$$

Where:-.

*S* (*t*) is a pure EEG signal,

*N* (*t*) is the artifact,

*E* (*t*) represents the recorded signal and t is the time when recording has been taken.

The presence of these artifacts introduces spikes that can create issues while reading neurological rhythms. So many methods have been proposed and presented by scientists and researchers to perform the artifacts removal process in EEG.

**Figure 10.** *Line interference of 50 Hz.*
