There are some subtle audio clues that I use to tell if my computer is doing something – mostly, whether I can hear the hard drive churning or the CPU fan whirring up to a higher RPM – these tell me that something is going on.
When I’m remote controlling computers, it’s a bit disturbing to have absolutely no audio feedback to my actions. Often times I have to ask the person on the other end “is anything happening?” because without sound, I can’t tell what’s going on.
I suppose I just find it interesting how much I rely on sound to tell me what the computer is doing. Something future computer designers should take into account!