| DirectX SDK | 
The IDirectSound3DBuffer::SetMaxDistance method sets the current maximum distance value.
HRESULT SetMaxDistance( D3DVALUE flMaxDistance, DWORD dwApply );
If the method succeeds, the return value is DS_OK.
If the method fails, the return value may be DSERR_INVALIDPARAM.
The default maximum distance, defined as DS3D_DEFAULTMAXDISTANCE, is effectively infinite.
  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.
IDirectSound3DBuffer::GetMaxDistance, IDirectSound3DBuffer::SetMinDistance