|Microsoft DirectX 9.0|
Rolloff is the amount of attenuation that is applied to sounds, based on the listener's distance from the sound source. DirectSound can ignore rolloff, exaggerate it, or give it the same effect as in the real world, depending on a global parameter called the rolloff factor.
The rolloff factor can range from DS3D_MINROLLOFFFACTOR to DS3D_MAXROLLOFFFACTOR, defined as 0.0 and 10.0 respectively. A value of DS3D_MINROLLOFFFACTOR means that sounds remain at full volume regardless of their distance from the listener. Every other value represents a multiple of the real-world rolloff.
The rolloff factor is global. To change the effect of distance for an individual sound buffer, you can set the minimum distance for the buffer.