If the pro is using the same cooling fan/liquid metal technique as the base ps5 then I think the decibels will be roughly the same.The PS4 Pro was a jet engine but judging by the fact that the base PS4 itself was much louder than the PS5, I wouldn't worry too much. While not completely whisper-quiet, the PS5 is close to that and really unobtrusive so I don't expect the Pro to fare much worse but you never know, we have to wait for actual tests.