In a method, device and computer program product for extracting an EMG signal out of a raw signal obtained with a number of electrodes, the electrodes being adapted to interact with a patient to obtain signals from the patient's diaphragm on respective channels associated with the electrodes, a signal-to-noise-ratio is determined for the raw signal in each channel, and a weighting factor is automatically determined dependent on the signal-to-noise ratio. The respective raw signals from the channels are weighted according to the weighting factors, and are summed in order to generate a sum signal that represents the total EMG signal contained in all of the raw signals.