Sorry Lomapaseo,
Cannot direct you to a source, just has been reported a number of times that RR claim to have solved the noise issue on open rotors.
After the T900 issue on the Qantas A380, the fan containment issue may be a point, although we have been spinning open propellers for a few years, and do not fully understand why the open rotor fan(or propeller) should be such an issue.
In my simplistic way, I fail to see so much difference between a turbo-prop and the open rotor except for the physical size of the beast.
Does not answer your question I know, but thats what age does for you.
Cheers.