An end of a detection body provided contactable with an upper side peripheral surface of a coin rolling on a coin path hooks into reeding of the coin, and thus the detection body is moved to a moving direction. An apparatus operable to perform the aforesaid method is also provided. As a result, the useful life and the functionality of the locking device is considerably improved. an audio signal and of a segment of a second signal e. A frequency offset is determined by comparing phase representation values which are shifted predetermined in time.