Loud buzzing in dashboard at freeway speeds

[Hookmaster]

The car is a 1996 Mercury Sable. At 65-70 mph, there can be a loud buzz coming from inside the dashboard. It sounds like it is behind the radio. I tried opening each window and the buzzing stopped only when the driver's window was opened. The buzzing changes pitch with wind buffeting the vehicle. Is this something with the ventilation system? Any ideas would be appreciated.

[delcecchi]

You didn't get a piece of paper down the defrost vents did you? Or maybe something on or in the cowl vents?

[Hookmaster]

I'll check that. I know where my daughter had it parked last fall would have gotten a lot of leaves falling on the car.

[delcecchi]

I asked about the intake at the cowl because my daughter had an old nissan stanza and the plastic over the intake had broken and leaves got down in there.

That nissan was a piece of junk, but that is another story....

[Lund79]

Could be wheel bearings. MY brother had a rattling sound coming from his dash and BIL said it was wheel bearings. My brother took it in and sure enough, the mechanic changed the wheel bearings and sound is gone.

[Hookmaster]

Wheel bearings are a long shot here. It's not a rattle or vibration but a buzzing like air going over something and vibrating it. Why would noise from bad wheel bearings stop when I open the driver window?

[Scott K]

You probably have a windshield seal bad. Grab a roll of duct tape, and apply it around the outsides of the edge of your windshield, see if the noise goes away. If it does, have it resealed.

[lispeej]

Maybe some loose change in or behind your ash tray?