A method and apparatus for reducing noise in brain signal measurements. The method provides an array of sensors providing for spatial oversampling, and multiple samplings over time to produce measurement data. The measurement data have a variance common to the sensors, and a remaining variance that can be safely assumed to be sensor or channel specific noise and that is accounted for by a suitable modification of the measurement data. The apparatus provides clusters of the sensors positioned in correspondence to the vertices of substantially equilateral triangles that are defined by tensile elements connecting the clusters.
