It's a classic experiment to play on your friends. Asking them to focus on the picture and not the sound simply play them two identical video clips of a few minutes long, but make sure that one is recorded with noisy / hissy or slightly distorted sound, and the same clip with clearer sound with good levels. Ask them which is the better PICTURE quality. They will ALWAYS insist the FIRST clip has much better picture quality.

Meaning? Properly recorded sound will add hugely to the perceived quality of and engagement with your film. Good sound makes any clip LOOK better. Its psychology.