Most of the rattlers I've come across have more of a high pitched buzzing sound; not the sound most of us associate with them. I heard one while wading and looked over to see this snake under a small sapling. Ever time the wind moved the branch, the snake would hit it. The leaves on that branch were pretty wilted.
interesting, my dog is a wuss, we heard a bussing bush and he lost his mind and chased us off, would not let me get closer and was barking at it like nothing I've seen, truly ferocious. later when we got home I played those sounds to see if it was what we heard (it was) and he lost his mind at the computer. apparently I have a snake protection dog.
got 3, the one in question is a bearded collie - herding dog and generally worthless for protection, which is why we have a pair of shepherd mixes but they didn't think we needed protection from a snake.