Question

Why is it important to record audio of silence in the area in which you are filming?

Answer 1

That depends. The answer I would give is so if something does arise, such as a really big noise accompanied by a really big animal, then you'd have more than just video. If a natural disaster occurs, the only way to tell may be through audio.

Answer 2

To make sure that there is no other outside/excess noise while you are filming your actual film

Hoped this helped !

Cheers, Z