Abstract: A sensor system for an aircraft for determining the air velocity of air flowing past the aircraft includes a first sensor and an evaluation device. The first sensor is configured for being arranged at the structure of the aircraft and determines a first response of the structure to a first local pressure fluctuation of a boundary layer of the air flowing past the aircraft. Furthermore, the first sensor generates a first signal on the basis of the determined first response of the structure. The evaluation device is configured for processing said first signal and for determining the actual air velocity on the basis of the first signal.

Abstract: A piezoelectric loudspeaker has a membrane and at least two flexural piezoresonators, one end of which is fixed, while the other end acts mechanically upon the membrane. The membrane is a flat membrane or a conical membrane having an aperture angle smaller than 10.degree..