Sound Processing Unit

I wonder why high-end sound cards such as Audigy or Audigy 2 are not called as ‘Sound Processing Units’ or SPUs or even ‘Audio Processing Units’.

If modern graphics cards can be called as GPUs or VPUs, why can’t sound cards be called as SPUs or APUs ?

Is there any special criteria that a sound card must fullfill in order to be recoqnise as SPUs or APUs?

Another question regarding EAX enhanments by Creative. If I use EAX for music and games, does that mean the sound card is using hardware acceleration ? If it does, will the CPU work less if I enable EAX ?

EAX is a hardware feature of the Creative cards that support it. I think some other cards, like the Terratec ones, do emulate it (but I am not really sure about that!).

Why expensive card got such names? Many of those offer real 24bit/96kHz (SB Audigy can do this only partually!) and far better frequency cuvers than normal cards do.

Some brands that produce very nice cards: Roland, Yamaha, Terratec etc…