Hi.  I need some advise please.  Our 05 plate fusion has a whining noise. It's not engine related 

The noise sounds like the one you got as a kid when you placed a blade of grass between you thumbs and blew across it

 Here are my observations

It only occurs  at about 75mph or above

Open a window a crack it stops.

if driving into a wind it starts at a lower speed.

with a tail wind the starting point is a higher mph

heater fan or off has no effect

postion of air flow has no effect. 

I suspect the onset is air pressure related

Has as anyone ever had a similar issue  or heard of itand if so  how was it solved or where do I start looking to solve

many thanks

chris

 

 

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Check there's nothing caught underneath the car, also check there's no dry leaves caught anywhere in the engine compartment that will rattle about as the draught catches them! (You'd be amazed how loud a trapped leaf can be)