OUr dog has gone deaf with older age, but can still hear if we yell really loudly, but only certain words. Not his name, Merlee, for instance, but he can hear "DOG!" :-) He was trained with hand signals, so we just have to be sure he can see us and, yes, he responds to vibrations, foot-stomping or pounding on the wall.
I wouldn't use most of those with a cat, though, as I think it would startle and frighten them too much and, I would never let a deaf cat out. We don't let Merlee run loose out on the desert or wherever we might go because he just wouldn't hear if there were any danger. He has always stayed close-by, but not always looking in our direction, so it's just too risky.
My hearing cats know some hand signals and they know what certain kinds of touches mean. I'd just try to be within the kitty's vision and be as calm and helpful as possible. It must be disconcerting to them. I know Merlee doesn't seem to understand sometimes, by the look on his face, just why he can't hear the neighbour dogs, etc.
One last thing: have you had the vet check it? My son's cat seemed deaf and she is old, but it was just a lot of wax build-up.