-Venin is correct, but the point is made.
Rattlers don't necessarily rattle before they strike. If you do see/hear one, just stand still for a spell, LOOK around, and if you spot it (sometimes a mate, too),, Just go the other way.
Few people in AZ get snakebit, but if it's gonna happen, hikers and us have the best chance. Be alert to it, but don't get paranoid.
If bitten, sticking your bit place in a ice chest is best 'till you get to a hospital. Don't try sucking out the poison, tourniquet, that sort of thing. (More damage can result from a turniquet than just ice on the wound).