Signal acquisition is stable, but with 2 channels of EEG, it’s especially important that both sensors of Emotiv MW20 maintain good contact to ensure optimal signal quality and for the mental state detections to run reliably. Our experience with MN8, with exactly the same sensor geometry as Emotiv MW20, indicates that session to session sensor placement accuracy is extremely stable and consistent between users. This makes sense because the sensors are located in the outer ear canals, with references placed on the ear flaps using the retaining hooks. Audio signals are optimised when the sensors seal the ear canal, which limits the rotational positioning range of the device, so the reference position is also very stable.