Sonotrodes are used when examining substances on the basis of acoustic levitation. In order to obtain a reproducible measurement result or to extend the possible uses of devices of this kind, the respective sonotrode has to meet a whole range of requirements. Exact tuning of the frequency and clean interaction between the sonotrode and a frequency generator are particularly important. The present invention proposes that a sonic horn and a main body of the sonotrode are provided as different parts and, in this case, the sonic horn can be mounted on or in the main body in a specific manner, in particular for operation at low voltage in such a way that the amplitude or operating voltage remains below a comparatively low maximum low-voltage value, in particular 50 Vpp. The formation of heat can be prevented in this way. The present invention further relates to a control or production method for a sonotrode apparatus of this kind. In this case, it is respectively possible to extend the range of use and to improve the reproducibility or quality of the measurement results.