The device determines the pulsating air mass flow in an internal combustion engine. The device includes a sensor producing an output signal to be evaluated to determine a pulsating air mass flow and a filter device for filtering the output signal to produce a filtered signal in which the signal components characteristic of the air mass flow pulsations and dynamic changes are not attenuated but noise and other spurious signals are attenuated. The filter has a bandpass characteristic with an adjustable center frequency which can be varied as a function of rotation speed as well as a low-pass characteristic. A controller of the internal combustion engine is used to adjust the center frequency of the bandpass characteristic according to engine rotation speed.