What are audio materials?
Why should you care?
tl;dr version: audio materials affect your footstep sounds, how walls block sound, and reverb — that's like how a giant concrete warehouse is gonna sound a lot more echoey than a small room covered in carpet.
Even if you've never created anything before in Sansar, you can play with audio materials in a few minutes. And if you're already experienced at the visual side of things, this will boost your audio skills! Seriously. It's fun and makes your experiences better when you have what I like to call "sight-sound cohesion"... walking on metal feels more immersive and cool when it sounds like that.
For more info, see the "Using audio materials" article!