All animals have strong survival instincts -- and deaf ones are no different. Deaf cats adapt to a silent world, quite effectively if they have the help of loving owners who learn to optimize nonverbal communication.
Getting His Attention
Before any communication can take place, you'll need to find him and get his attention. A noisy bell on his collar will help you to locate him, but you'll greatly improve communication by helping him to find you. In time, these methods may teach him to cry out for a nonverbal response that gives indication to your whereabouts.
For instance, you could create a sonic resonance by stomping the floor to get him to look at you. At close range, creating air vibration with a sharp hand clap might be enough to catch his attention, if the cause of his deafness hasn't affected his ability to sense vibrations. Or you could flick a light switch.
The most effective solution might be to carry a small flashlight. You can spotlight him or the space in front of him to get him to look your way from a distance. The flashlight is handy for casting moving shadows that will cause a deaf cat to look around or to pinpoint you if he's already looking. If, when he does notice you, you reward him with a tasty treat or other motivator, he may eventually run to you when signaled. And how many cats that can hear do that?
Once you do get his attention, a few hand signals -- such as wide hand waves, floor tapping or finger-pointing will serve to communicate commands or to react positively or "negatively" to your cat's behavior -- just as you would verbally. Try to keep the signals simple, and always reinforce his good behavior with gentle petting and treats; withhold the rewards for bad rather than introduce punishment or negative reinforcement.
Facial expressions speak volumes -- ask any frosted husband who has innocently forgotten a wedding anniversary. Your cat will watch your face and associate the facial expressions with your reaction to his behavior. Play it up and be expressive: Smile broadly when your kitty is good, and present him with a wicked glare when he is not.
Communicating Through Play
Playtime communication and interaction are important to cats; they can be critical to a deaf cat in relieving stress. Utilizing hand signals and facial expressions while playing simple cat-and-mouse games with your pet can improve communication and be therapeutic for both of you.
It's important to note that your deaf cat's remaining senses tend to be more acute -- especially vision and touch. Any toy that is shiny or glitters, like a diamond necklace, is especially attractive to him. And quivering playthings, like your cell phone set on vibrate, will thrill him for days on end. Experiment, and introduce new stimulation regularly for his mental health.