ELECTROENCEPHALOGRAPHY (EEG) SIGNAL ANALYSIS FOR THE CASE OF VIRTUAL REALITY (VR) ON TWO DIFFERENT LEVELS/TYPES OF VISUAL MOTIONS

• Main Author: Nur Sakinah, Feby
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/67661
• Institution: Institut Teknologi Bandung

Metaverse is a virtual environment that is made very similar to the real environment so that users can interact freely in it, which is a development of the concept of virtual reality (VR). VR can cause symptoms such as nausea, dizziness, and fatigue, called visually induced motion sickness (VIMS). VIMS symptoms from VR can be determined using a simulator sickness questionnaire (SSQ) and electroencephalography (EEG). SSQ data from subjects were grouped into three categories, namely nausea (N), oculomotor (O), and disorientation (D), and multiplied by the weight factor of each category. Neuron Spectrum-63 (19+2 electrodes) is used for EEG and the Oculus Quest 2 head-mounted display (HMD) is used for VR so that users can feel the atmosphere around them. Each subject is given two levels/types of visual motions in VR: slow translational motion (VR1) and faster rotational motion (VR2). This study aims to obtain the power spectral density (PSD) value, the shift in the peak frequency value of the brain waves, and the change in the SSQ value due to the influence of VR1 and VR2. The EEG raw data were processed using MATLAB and EEGLab by doing centering, filtering at the theta band frequency (4 – 8 Hz), the alpha band (8 – 13 Hz), the beta-1 band (13 – 20 Hz), and beta-2 band (20 – 30 Hz). The data are then processed using the Welch Periodogram to get the PSD value in the frequency range. This study was conducted on 18 healthy male subjects aged 19-26 without a history of brain disorders. Data were measured when the subject was at rest as baseline (eyes closed and eyes open) and during VR. When the eyes were closed, the PSD of the theta band and alpha band increased after VR1 and VR2, there was no significant change in the level/type of VR for the theta band, while there was a significant change in the parietal lobe for the alpha band. The theta peak frequency increased, and the alpha peak frequency decreased. This suggests that there is a somatosensory effect during VR. When the eyes were opened, the theta band and alpha band PSD increased after VR, especially in the frontal and parietal regions but had no significant change in the level/type of VR. The theta peak frequency value decreased after VR1 and VR2, while the alpha peak frequency increased after VR1 but decreased after VR2. The research found that there was an increase in the SSQ value to the level/type of VR given to the subject. VR2 gives a significant difference to the total score of SSQ than VR1. During VR1 and VR2, theta PSD activates the frontal lobe while alpha PSD activates lobes that vary in each subject. The increase in theta and alpha band PSD indicates the severity of VR exerted on information processing in the frontal lobe and the somatosensory effect on the parietal lobe. During VR, the theta PSD in the frontal lobe states the processing of information by the subject about VR. The activated lobe by alpha PSD was shifted from frontal lobe to other lobe and this is may influenced by the visual stimulus that explains the subject's response to motion sickness symptoms.