How much do headphones interfere with the EEG signal? Is there a difference between the amount of interference from over-ear headphones (if you can fit them) and in-ear headphones?

Edit: another beginner question- what brain areas do each of the four raw EEG channels (/muse/eeg (0)), (/muse/eeg (1)) … correspond to?

One more question: Where can I read about how the data in the Muse IOS app analyzed? I am doing a research project and anything that can tell me more about what’s going on under the hood in the app would be very useful.