|Microsoft DirectX 9.0|
In a virtual 3-D environment as in the real world, sounds exist only in relation to a point of reception. The 3-D sound effects in a DirectX application are affected not only by the position, orientation, and velocity values of the sound sources, but also by the position, orientation, and velocity of the virtual listener.
By default, the listener is stationary at the zero point of all vectors, oriented with the nose toward the positive Z-axis and the top of the head toward the positive Y-axis. The application can change all these values to reflect the movement and facing of the user within virtual space. The listener object also controls the general parameters of the acoustic environment, such as the amount of Doppler shift and the rate of volume attenuation over distance.
This section describes how your application can obtain a listener object and manage global 3-D sound parameters. The following topics are discussed: