Activity trackers have come a long way. Today, Boston-based company Neurable announced the launch of its smart headphones, dubbed the MW75 Neuro, which use electroencephalography, or EEG, and artificial intelligence to track the wearer’s focus levels by reading their brain waves. Noninvasive BCIs like Neurable’s collect brain data though the skin—usually with EEG—without requiring any kind of surgery. EEG is …