humming bloody mondeo

[niceonebruvva]

Hi first time on here need help!!!!
I own a 2.5 ghia X 97reg mondeo which is very well maintained but every time the engine gets nice and warm I'm getting a realy loud hum only on idle, please please please someone have an idea how to fix it, it seems to come from the air filter pipes, I have tried moving them so they sit in a diferent way but with no joy look forward to any ideas you may have CHEERS