Sound buffers have three processing modes: normal, head-relative, and disabled. Normal processing mode is the default mode. In the head-relative mode, sound parameters (position, velocity, and orientation) are relative to the listener's parameters. In this mode, the absolute parameters of the sound are updated automatically as the listener's parameters change, so that the relative parameters remain constant. In the disabled mode, 3D sound processing is disabled and the sound seems to originate from the center of the listener's head.
An application sets the mode for a 3D sound buffer by using the IDirectSound3DBuffer::SetMode method. This method sets the operation mode based on the flag the application sets for the first parameter, dwMode.