Meh. Actually, the Darth Vader one doesn't seem that out of place, if anything i always thought it was kind of weird that he doesnt say anything during that particular scene.
As for the obi wan one, well it sounds a little silly, but i get why its been done, it's meant to sound like he's using the force to make an intimidating noise, where as before it just sounded like he was blowing on a whistle or something, and why that scared the freakin sand people, with their guns and chanting, i never really understood.