In extracting frequency bands from EEG signals, using PSD is a more suitable approach. PSD provides an accurate representation of the distribution of power across different frequencies, which is ideal for identifying alpha, theta, beta, and gamma bands. While the absolute value of the STFT can illustrate how the signal's spectrum changes over time, it may not adequately distinguish the power contribution of the different frequency bands. Thus, to isolate these bands, compute the PSD from the complex-valued STFT and segment the resulting spectrum into the respective frequency bands.