This morning I took a stand in and set it up in a different area than normal. I couldn't believe the number of squirrels, I could see 8 at one time. Most of the time you can move slowly in your stand and they won't notice you, even when they are within 10 yards.
Today after rattling I got one worked up and he sat 10 feet from me and barked up a storm. I just sat still and he quit and moved on. Within a few minutes he was back on the ground gathering nuts.
I think deer do listen to squirrels and birds, but remember deer will also cause some squirrels to bark and chatter.
I'll see the squirrels on the ground start running up trees and know that a deer is coming.
A deer will rely on all of his senses but primarily their nose when alarmed. Some people say you can fool a deer's vision and hearing twice, but with their nose you have one chance.