The present invention relates to a device for process monitoring during resistance spot welding and/or resistance projection welding, comprising at least one electrode (1) for resistance spot welding and/or resistance projection welding of at least one workpiece (4) and at least one current/voltage source (6) connected to the at least one electrode (1). Furthermore, at least one detection unit (2) is provided, which is designed to detect at least one airborne sound parameter during welding. Furthermore, at least one evaluation unit (5) is provided, which is designed to decompose the detected airborne sound parameter into a continuous spectrum (8) by means of a Fourier transformation, wherein the evaluation unit (5) is designed to compare the continuous spectrum (8) with a template signal (7), whereby a defect pattern can be clearly determined.