Abstract: A vibration exciter comprises a main body having a relatively large mass; a relatively light-weight dynamic part, to be flexibly supported so as to be movable relative the main body, and driving means for driving the main body and the dynamic part to move relative to each other, or at least generate a force acting between the main body and the dynamic part, under the influence of a control signal. It comprises coupling means for providing a releasable coupling between the main body and the dynamic part, the coupling means comprising at least one coupling element releasably engaging one of the main body and the dynamic part in a coupled condition, the coupling element being arranged on the other one of the main body and the dynamic part so as for the dynamic part to be flexibly supported on the main body in the coupled condition via the coupling element.

Abstract: Described is a device for creating a sound source comprising integrated measuring means (50) for measuring a property representative of the strength of the sound source, the device comprising a sound generator (40a, 40b) for generating sound within an annular space defined around a central axis, the device comprising a pair of guiding surfaces (113, 123) for guiding sound away from the annular space in opposite directions along the central axis. With sound being guided as described, sound in addition being allowed to propagate outside the device in a radial direction with respect to the central axis, a high degree of omnidirectionality of the created sound source is attained.