The listener's orientation plays a strong role in 3D effects processing. DirectSound approximates sound cues to provide the illusion that a sound is generated at a particular point in space. For more information about these cues, see Perception of Sound Positions.
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:
An application can set and retrieve the listener's orientation by using the IDirectSound3DListener::SetOrientation and IDirectSound3DListener::GetOrientation methods. By default, the front vector is (0,0,1.0), and the top vector is (0,1.0,0).