I am confusing about a 60 Hz notch-filter.
When we use EEG signals, all waves (Delta, theta, alpha, beta, gamma) are located lower than 60 Hz. For example, alpha wave ranges from 8 to 12.99 Hz and beta wave ranges from 13 to 29.99 Hz. Thus, when we extract the frequency for analysis, the frequency does not include 60 Hz frequency. (If alpha wave, it’s 8 to 12.99 Hz - so it does not include a power line noise)
So I think that applying a 60 Hz notch-filter has no effect to the analysis result, but most papers use a notch-filter to remove a power line noise. In the situation above, what is the role of a notch filter?