A method for shielding a measuring device comprising an assembly of sensors (10, 45) that are adapted to measure biomagnetic signals from external magnetic interference signals, the method comprising providing the assembly of sensors with at least one magnetic feedback, wherein a difference signal of the at least one magnetic feedback is obtained from sensors of the aforementioned assembly of sensors; c h a r a c t e r i s e d in that the method further comprises: producing in a region of the assembly of sensors a magnetic field that compensates for external interferences with at least one actuator (12, 13, 42, 43) disposed outside the assembly of sensors; wherein the difference signal that produces a compensation voltage in the at least one actuator is a linear combination of the signals of more than one sensor from the assembly of sensors; using a signal space separation method, sss, to separate the measured biomagnetic signal from signals originating from outside the measurement region, which signals are produced by the at least one actuator and the external interferences, in a geometry where an interesting source generating biomagnetic signals is disposed in measurement volume V1, sensors are disposed outside volume V1 in volume V2, and sources of magnetic interferences and the at least one actuator is outside volume V1 and V2 in volume V3 wherein the sss method further comprises parametrising a magnetic field produced by said interesting sources corresponding to biomagnetic signals disposed in volume V1 in volume V2 as a sum of elementary fields, each of which is irrotational, sourceless and finite outside volume V1 so that a desired accuracy is achieved for the parametrised magnetic field in volume V2; parametrising the sum magnetic field produced by the interference sources and the at least one actuator disposed in volume V3 in volume V2 as a sum of elementary fields, each of which is irrotational, sourceless and finite outside volume V3 so that a desired accuracy is achieved for the parametrised magnetic field in volume V2; calculating a signal vector of the measuring device corresponding to each elementary field; measuring the magnetic signal using sensors of the assembly of sensors; and separating the fields produced from sources disposed in the volumes V1 and V3 by calculating the components of the measured signal vector in the basis formed by the signal vectors associated with the elementary fields. producing in a region of the assembly of sensors a magnetic field that compensates for external interferences with at least one actuator (12, 13, 42, 43) disposed outside the assembly of sensors; wherein the difference signal that produces a compensation voltage in the at least one actuator is a linear combination of the signals of more than one sensor from the assembly of sensors; using a signal space separation method, sss, to separate the measured biomagnetic signal from signals originating from outside the measurement region, which signals are produced by the at least one actuator and the external interferences, in a geometry where an interesting source generating biomagnetic signals is disposed in measurement volume V1, sensors are disposed outside volume V1 in volume V2, and sources of magnetic interferences and the at least one actuator is outside volume V1 and V2 in volume V3 wherein the sss method further comprises parametrising a magnetic field produced by said interesting sources corresponding to biomagnetic signals disposed in volume V1 in volume V2 as a sum of elementary fields, each of which is irrotational, sourceless and finite outside volume V1 so that a desired accuracy is achieved for the parametrised magnetic field in volume V2; parametrising the sum magnetic field produced by the interference sources and the at least one actuator disposed in volume V3 in volume V2 as a sum of elementary fields, each of which is irrotational, sourceless and finite outside volume V3 so that a desired accuracy is achieved for the parametrised magnetic field in volume V2; calculating a signal vector of the measuring device corresponding to each elementary field; measuring the magnetic signal using sensors of the assembly of sensors; and separating the fields produced from sources disposed in the volumes V1 and V3 by calculating the components of the measured signal vector in the basis formed by the signal vectors associated with the elementary fields.