A head tracking system that determines a rotation angle of a head of a user with respect to a reference direction, dependent on a movement of a user including changes of place, position, and/or posture. The head tracking system includes a sensing device for measuring a head movement to provide a measure representing the head movement, and a processing circuit for deriving the rotation angle of the head of the user with respect to the reference direction from the measure. The reference direction is dependent on the movement of the user.