Here is an interesting Nova article I found today. It talks about the different way barks sound and what they mean. There is an interactive game you can play to try and identify the meanings. I did pretty horribly... how about you?
When Rouser barks, it sounds vicious and much scarier! No missing what he's saying when someone isn't invited into our home or backyard. And when he wants to go for a walk, he sounds like Chew-baca.
When he wants to eat or see if there is any hope that he is going with us as we collect up our things to leave, he gives us very specific and silent stares. Deep into our eyes.
I just played this for my husband (and Rouser who happened to be in the room).
Rouser DID NOT like the "Stranger" bark and ran over to my computer and woofed.
Then when he heard the attack dog, he barked a few times and ran over to my husband (who was sitting on the floor) and backed into him and sat on his lap (all 90 pounds of him).
Funny, though, when we played the "I want the ball" clip he looked around like he does when he's trying to find a nearby toy. We stopped after that as Rouser was starting to pant and show other signs of stress - I don't think he liked this experiment.