Head tracking, system and an audio reproduction system

A head tracking system (400) is proposed in the present invention that determines a rotation angle (300) of a head (100b) of a user (100) with respect to a reference direction (310), which is dependent on a movement of a user (100). Here the movement of a user should be understood as an act or process of moving including e.g. changes of place, position, or posture, such as e.g. lying down or sitting in a relaxation chair. The head tracking system according to the invention comprises a sensing device (410) for measuring a head movement to provide a measure (401) representing the head movement, and a processing circuit (420) for deriving the rotation angle of the head of the user with respect to the reference direction from the measure. The reference direction (310) used in the processing circuit (420) is dependent on the movement of the user. The advantage of making the reference direction (310) dependent on a movement of a user is that determining the rotation angle (300) of the head (100b) is independent of the environment, i.e. not fixed to environment. Hence whenever the user (100) is e.g. on the move and his body parts undergo movement the reference direction is adapted to this movement.