The German magazine ComputerBild is currently running an analysis with a PS4 debug unit. They have measured the unit's noise level while navigating the system menu and compared it to the original PS3.
After 10 minutes of operation
PS3: 0.83 sone
PS4: 0.815 sone
According to the magazine, a "slight noise" is audible from 40cm (= 15.75 inches) distance.
After 60 minutes of operation
PS3: 2.1 sone
PS4: 0.83 sone
A sone is a unit of perceived loudness: http://en.wikipedia.org/wiki/Sone (with examples).
Source: http://new.livestream.com/accounts/3796398/events/2475845
After 10 minutes of operation
PS3: 0.83 sone
PS4: 0.815 sone
According to the magazine, a "slight noise" is audible from 40cm (= 15.75 inches) distance.
After 60 minutes of operation
PS3: 2.1 sone
PS4: 0.83 sone
A sone is a unit of perceived loudness: http://en.wikipedia.org/wiki/Sone (with examples).
Source: http://new.livestream.com/accounts/3796398/events/2475845