Listeners experience an identical sonic effect when an object moves in a 90-degree arc around them or if they move their heads 90 degrees relative to the object. Programmatically, however, it is often much simpler to change the position or orientation of the listener than to change the position of every other object in a scene. DirectSound makes this possible through the IDirectSound3DListener interface.
Listener orientation is defined by the relationship between two vectors that share an origin: the top and front vectors. The top vector originates from the center of the listener's head and points straight up through the top of the head. The front vector also originates from the center of the listener's head, but it points at a right angle to the top vector, forward through the listener's face. The following illustration shows the directions of these vectors: