An air intake system for an internal combustion engine in which the air, which is taken in, passes via an air filter (3) to the internal combustion engine through an intake passage within which a damping cavity volume (5) is provided which acts as a Helmholz resonator. The effective damping cavity volume (5) is sized such that a given noise frequency range can be attenuated, and in order to achieve optimum noise suppression, at least a partial flow of air passes through the damping cavity volume, and the size of the effective damping cavity volume (5) through which the air passes can be varied by reversible switches and/or valves.