US Patent 8243946 Personal acoustic device position determination

Apparatus and method for determining an operating state of a personal acoustic device by receiving a signal from one or more movement sensors indicating movement detected by the one or more movement sensors, wherein the one or more movement sensors are disposed on portions of the personal acoustic device structured to be worn on a user's head to enable the one or more movement sensors to detect rotational movements of a user's head when the personal acoustic device is in position on the user's head such that a casing of the personal acoustic device is adjacent an ear of the user.