A CMOS structure is disclosed in which a first type FET has an extremely thin oxide liner. The hammer is rotatable together with the anvil. During operation of the electric motor a virtual speed and a virtual gear-shift stage are continuously determined from at least one first operating parameter describing the operational state of the motor vehicle and an acoustic output, in particular an output of an engine noise, takes place on the basis of the virtual speed and the virtual gear-shift stage. The second input signal is a test offset voltage in a test range.