I have a similar problem that is present when accelerating or decelerating. The noise rises and falls with engine RPM. I posted this a while back and someone suggested the air con. Sure enough when it is switched off it disappears immediately, turn it on and it's there again. Sounds just like a noisy worn bearing and it's getting worse.
What is so irritating about all this is that the 1.0 turbo is a quiet motor so a noisy aircon spoils that feature. Dealer says it is normal !!! Ford spend many millions developing a quiet super little turbo motor and this is what you get.
Nice to know what is causing the problem. At first I though the turbo was getting noisy but now I know what is causing it does anyone know the cure?