A grinding machine includes a holding table adapted to hold a workpiece, a grinding unit operative to grind the workpiece held on the holding piece, and a grinding unit transfer mechanism operative to shift the grinding unit in a direction coming close to or moving away from the workpiece. According to the invention one fills the mold frame, with the exception of an area which surrounds and is in close proximity to the hollow space, with a plurality of filler elements, which are formed into at least an essentially incompressible shape. The transmitting section is attached to the detecting section. Embodiments further analyze the performance data to identify a cluster of services that each follow a pattern of performance data. The locking mechanism comprises a rack mounted on one of the hand grips and a pawl mounted on the other hand grip, each of which have teeth adapted to mesh with each other to hold the jaws in the predetermined closed position. Then the useful signal component contained in the listening signal is compared with the listening signal itself, and the electrical useful signal is adapted in dependence on this.