A device for the treatment or processing of surfaces, comprising: - an actuator (5a to 5i) for acting on a workpiece surface or for processing a workpiece surface, - at least one sonotrode which has a sound-radiating surface and is connected in a mechanically rigid manner to the actuator (5a to 5i) to form a work unit, and - a movable positioning device coupled to the work unit, for positioning the work unit in a position opposite the workpiece surface, wherein - the positioning device has a force-applying member or uses gravitational force in order to urge the movably suspended work unit with a predetermined urging force in the direction of the workpiece surface, - the sound-radiating surface of the sonotrode generates ultrasonic vibrations such that, in the presence of a gaseous medium, an ultrasonic levitation force field acts between the workpiece surface and the sound-radiating surface of the sonotrode, which generates a counterforce against the urging force, whereby the work unit is held hovering at a distance from the workpiece surface, the actuator (5a to 5i) being adapted to - apply liquid, pasty, powdery or aerosol-like media on the workpiece surface, or - generate electric, magnetic or electromagnetic fields or a plasma on the workpiece surface in order to thereby change the workpiece surface, or - generate an ultrasonic field for changing the workpiece surface, or - act on the workpiece surface by means of mechanical operating agent for removing material. - an actuator (5a to 5i) for acting on a workpiece surface or for processing a workpiece surface, - at least one sonotrode which has a sound-radiating surface and is connected in a mechanically rigid manner to the actuator (5a to 5i) to form a work unit, and - a movable positioning device coupled to the work unit, for positioning the work unit in a position opposite the workpiece surface, wherein - the positioning device has a force-applying member or uses gravitational force in order to urge the movably suspended work unit with a predetermined urging force in the direction of the workpiece surface, - the sound-radiating surface of the sonotrode generates ultrasonic vibrations such that, in the presence of a gaseous medium, an ultrasonic levitation force field acts between the workpiece surface and the sound-radiating surface of the sonotrode, which generates a counterforce against the urging force, whereby the work unit is held hovering at a distance from the workpiece surface, the actuator (5a to 5i) being adapted to - apply liquid, pasty, powdery or aerosol-like media on the workpiece surface, or - generate electric, magnetic or electromagnetic fields or a plasma on the workpiece surface in order to thereby change the workpiece surface, or - generate an ultrasonic field for changing the workpiece surface, or - act on the workpiece surface by means of mechanical operating agent for removing material. - apply liquid, pasty, powdery or aerosol-like media on the workpiece surface, or - generate electric, magnetic or electromagnetic fields or a plasma on the workpiece surface in order to thereby change the workpiece surface, or - generate an ultrasonic field for changing the workpiece surface, or - act on the workpiece surface by means of mechanical operating agent for removing material.