I've learned that NAT was natural sound and that NAT is some times good and sometimes bad. sometimes when you have a lot of natural sound it can drown out your charter or what ever you were filming. most of the natural sound you get can be helpful so lets say that you we're shooting a scene outside and you want to give your audience a since of being out there with them then you just get all the sounds that are around you and boom there you go.
- there is a difference from noise and natural sound.