My wife is completely deaf (one complication from having been born very prematurely) and we like to ride tandem bikes together. She's understandably hesitant to ride solo due to the dangers.
Motorbikes are different though. I've been a hardcore mountain biker for over a decade, with extremely fine tuned reflexes and "feel" of how me, the bike, and the ground are interacting. But the motorbike has me all out of sorts! I'm no longer in a proper gear until it is too late. I feel like I have less traction because I'm not directly involved with the bike anymore, only steering it, it seems. And overall speeds are 90% of the time much greater than without motor, double the speed and you quadruple the energy of impact and friction IF you go down. Triple speed, nine times the energy. But worst of all for a deaf person, are missing the sounds made before something goes wrong. I heard my chainguard starting to break in the rear just before it got chewed up into the gears, likely skidding me out into traffic.
Granted, you can still feel that there is a problem, and after experienceing all problems, will learn how they each feel, but you'll feel than AFTER they happen.

Is it inherently more dangerous for a deaf person? Not really. Only from swerving yourself into the path of a car. Driver's are equally stupid to everyone. If they hit you, it's not because you're deaf.
It is FAR more dangerous to ride against the flow of traffic. You certainly FEEL safer and in more control, but vastly increase chances of trouble. Riding with the flow of traffic allows drivers more time to see/react to you, and as long as you a one, two, or three flashing red taillights, they'll see you (usually!)
Play the game that i do (20 miles trip on curvy mountain highway, 15 of it with only six inches of shoulder) hug the line. Practice steering control to maintain a line as perfectly as possible, and if there's an object in your path, start to move out well before it, so you don't suddenly veer around it. Most importantly, practice the "Messerschmit twitch". From the air force pilots having to rapidly twitch their head around to take in a great deal of information without steering the plane off it's course. Practice looking bake without steering....vital talent. Practice, practice, practice! Remember, at 35 mph, hearing people are deaf to what is coming up behind them unless it's a mufflerless Harley.