Toss a rock into the river. The splash consists of two things — the impact we see and the impact we hear. The impact we see sends ripples across the water; the impact we hear is from ripples in the air. A little rock produces little ripples and a little sound. A big rock produces big ripples and a big sound.
The sound validates the impact and, at the same time, gives us a clue as to the size of the rock and whether the rock has hit the water flat (fwop) or on edge (fwip). Sound describes what we see. Stop and listen; sound also describes what we don't see. Sound accompanies us and can tell us where we are and who we're with.
Sound validates, describes, and accompanies. In Flash — with sound — a button can clank, the type can swoosh, and the whole darn site can rattle and hum.
