Hmm...well, rattlesnakes can't hear...they have no ears. But they do feel vibrations, so rather than making a lot of noise, stomping or walking heavily might work better.

With bears, on the other hand, most grizzly attacks occur because the bear was startled, so making noise in bear country is a great idea. (Even black bears are deterred by noise. I've heard, though, that this doesn't work as well with polar bears, and I have no idea about Kodiacs.)