| DirectX SDK | 
The IDirectSound3DBuffer::SetConeOutsideVolume method sets the current cone outside volume for this sound buffer.
HRESULT SetConeOutsideVolume( LONG lConeOutsideVolume, DWORD dwApply );
If the method succeeds, the return value is DS_OK.
If the method fails, the return value may be DSERR_INVALIDPARAM.
Volume levels are represented by attenuation. Allowable values are between DSBVOLUME_MAX (no attenuation) and DSBVOLUME_MIN (silence). The default value is DS3D_DEFAULTCONEOUTSIDEVOLUME (no attenuation). These values are defined in Dsound.h. Currently DirectSound does not support amplification.
For information about the concept of cone outside volume, see Sound Cones.
  Windows NT/2000: Requires Windows 2000.
  Windows 95/98: Requires Windows 95 or later. Available as a redistributable for Windows 95.
  Header: Declared in dsound.h.
  Import Library: Use dsound.lib.