I shoot every bow I have 3 under, and all of them have nock points between 5/8” and 7/8”, based on bare shaft tuning to get the bare shaft to fly slightly (2* or so) nock high. If you don't bare shaft tune, I would set the nock point at 3/4”, which might be more nock high than is optimal, but as long as it is true nock high and not shelf bounce, it doesn't matter that much. I believe the reason for the high nock points is to get your string fingers more in the same position on the string as they would be if you were shooting split fingers. But the “why” of it doesn't really matter; all that matters is getting good arrow flight. Arrow flight changes with the relative weight of fingers on the string, so figure out what works best for you and be consistent. Recommended weight distribution is having most of the weight on the middle finger, next most on the index finger, and very little weight on the ring finger. Some people leave the ring finger off the string entirely and shoot two under. A variation of this would be to leave the index finger off the string and shoot with the middle and ring fingers.
As to the noise, if the bow was tillered for split, it is going to be difficult to get the limbs to return at exactly the same time when you shoot 3 under. However, the noise can be minimized by all the usual methods: good tuning, string silencers, avoiding ultra-lightweight arrows (less than 9 gpp) etc. Good form and having a good release goes a long way to reducing noise also.