Maybe consider a TV cabinet/stand combo with closing front doors and put the PS4 inside that, it wont kill the noise but it might be able to muffle it enough that it is tolerable.
An example. https://www.amazon.com/Furinno-FL-800EX-Double-Casters-Espresso/dp/B014Q2PHC8/
Only other thing is to completely replace the Sony cooling system with something better like in the video below.