I started Teddy in a bag almost the day he came home (8 weeks old) So he could be in there for hours at a time and NEVER makes a sound. We even took him into a coffee shop for lunch today! What Have found is that to make sure they don't make any noise keep them totally covered so the can't see out. The only time Teddy has ever made a sound was when I make it so he can see what's going on. Give it a try!
Kim and Teddy