# Filtering the EEG signals

I have very limited knowledge of DSP, so I apologize if my question is trivial :)

I have an EEG signal from which I need to extract different frequency bands. For example, waves in the the frequency band of 8-12 Hz.

After noise filtering, I was planning to simply feed the data into the FFmpeg bandpass filter, setting the 'frequency' to 10 Hz, and 'width' to 2 Hz. Is this the way to do it?

I need to ask this since I'm not sure how to check if I got the correct wave in the end.

It is one way to do it, yes. You will get frequencies between 8 an 12 Hz less attenuated compared to others, but both the 8 and 12 Hz components will be attenuated 3 dB ($\frac{1}{\sqrt{2}}$ the original magnitude) and frequencies just outside the band will be attenuated only slightly more.