DirectSound uses the speaker configuration—that is, the position of the speakers relative to the listener—to optimize 3-D effects for the user's sound system.
In Windows 98 and Windows 2000, the speaker configuration can be set by the user in Control Panel. An application can retrieve this value by using IDirectSound::GetSpeakerConfig and override it by calling IDirectSound::SetSpeakerConfig.
In Windows 95, GetSpeakerConfig simply returns a default value or the last value you set with SetSpeakerConfig.