2.4 Puma engine blown sound

Hi, my 110 puma makes a strange noise above 30mph regardless of gear and regardless if the accelerator is pressed or not. I can only describe it as a quiet 50cc moped in the engine bay. It sounds like it is just outside of the window on the driver side under the bonnet. A moped or a blade of grass being blown. It is isn’t horrendous and may be perfectly normal but my 300tdi did not make that noise (appreciate it’s a different engine!) Have read that it may be a turbo gasket but if anyone can relate to the noise I am describing it would be good to hear from you. Worse above 30mph and particularly worse if going at speed with foot off the pedal is coasting downhill at around 45mph

Thanks

It could be either an undershield panel made loose, or a leak in an exhaust joint