Abstract: An electrode cap for obtaining EPM signals from a head of a subject, the cap comprising: (i) an insulating layer for positioning adjacent to the head of the subject; (ii) an electrically conductive layer comprising ionic conduction means, situated above the insulating layer so that in use, it is separated from the head of the subject by the insulating layer; (iii) a plurality of measurement signal electrodes extending through the electrically conductive layer and the insulating layer for contacting the head of the subject, the measurement signal electrodes being electrically insulated from the electrically conductive layer; and (iv) at least one reference node electrically connected to the electrically conductive layer;

Abstract: In an electronic apparatus and method for reducing interference in an EPM signal, there is provided (a) a signal line connected to a-signal electrode; and (b) a reference line connected to a reference electrode. The signal line and reference line are associated by being in close physical proximity for a substantial part of their lengths. Subtraction means subtracts an interference signal on the reference line from an interference signal on the signal line to enhance a desired signal on the signal line.