I haven't given birth in a hospital but that's because I know home birth is for me (and I haven't had any medical issues that would necessitate a hospital birth). I think it depends on the person how loud they are during birth. I was not loud at all and just made a lot of groaning noises. The question I would ask myself is- Am I comfortable enough to have sex in my apartment? If yes, then I would not hesitate to home birth. Or alternately, would I watch a sporting event on TV where maybe I would yell out in excitement a couple times?
You say you have a supportive OB and are still worried. How supportive is your hospital in general? If you do decide on the hospital, remember that if you get a nurse you don't like ask for a different one!
I also second the love for HypnoBabies!
For me, the ability to have more control at home and be more relaxed is of the utmost importance, and I believe it gives me the best chance of a safe and happy birth.