openal i think is graphic supported card.
look in the readme file.
i've read it somewhere.
this is from the read me file here.....
ADVANCED AUDIO OPTIONS
This game uses OpenAL, the standard audio library. It can drive sound cards with built-in
OpenAL support directly, or translate OpenAL commands to use DirectSound or DirectSound3D
drivers. Thus it offers both high compatibility and high performance.
You select a particular driver using the audio buttons in the Setup program. There are five
possible options. Any that do not suit your machine are ghosted, and a safe default is
selected after the game is first installed. Click on any of the other non-ghosted items to
try an alternative.
THE FIVE CHOICES
The "NATIVE OPENAL ACCELERATION" driver is generally the best, as it talks directly to
high-quality audio cards and supports the new EFX digital effects. However this does need
up-to-date drivers (Refer to section IX below).
The "NFORCE OPENAL 1.0" option uses an older version of OpenAL available on NForce audio
systems. You only get this option if you have suitable Nvidia hardware and drivers installed.
The "DIREXTSOUND3D TRANSLATION" driver translates OpenAL audio requests into the old
DirectSound3D format, to take advantage of drivers for systems that do not yet support
OpenAL natively. Digital effects will be translated to use EAX - DirectSound3D Environmental
Audio Extensions - in place of EFX, if possible. The quality and performance of this
translation depends on the compatibility of the underlying DirectSound3D driver and your
'hardware acceleration' settings in Windows. "DirectSound3D translation" is typically the
fastest option on Windows XP, but if the DirectSound3D driver has bugs (e.g. some RealTek
systems) performance suffers.