An apparatus for detecting irregularities in a rotation of roller bodies in a roller bearing, the apparatus comprising a measurement module and a processor module. The measurement module is operable to provide a deformation signal indicative of a deformation of a surface region of a bearing ring of the roller bearing, wherein the deformation is due to the rotation of the roller bodies over the surface region. The processor module is operable to extract one or more signal quantities of interest from the deformation signal and operable to provide statistical information on the one or more extracted signal quantities of interest.