You can actually hear Sam go through puberty in the second deleted scene for Hunted. I noticed in the one for Bloodlust that his voice sounded kinda high and nasally but didn't think a lot of it until I watched the last one.
For reference listen to the "Well, was it human?" line at approximately 00:31 and then anything at all past the 00:51 mark.
It really kind of amazes me how very little Jared's voice sounds like Sam's. Also? I have decided that before and during puberty Sam sounded like Jared, I realize that's redundant and sounds stupid but if you download the clip and listen you'll get what I mean.