What would cause a high pitched whistle under acceleration, at all speeds. on 2003 Chevrolet Silverado 2500 HD

This morning it sounded like I ran over some debris or something fell off. Next thing I know I'm hearing a whistle, almost like a jet engine. I took a quick look under the hood, but didn't notice anything unusual. I'll have to look up under the engine in the morning to take a closer look at the undercarriage.

Asked by for the 2003 Chevrolet Silverado 2500 HD
If it only does when the truck is in motion, remove that stick that's now rubbing on the driveshaft!
In other words look for something it picked up off the road when you "ran over some debris".
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Do you have an aftermarket cone air filter/cold air kit? I've seen these things laying on the shoulder of many roads. Definitely sounds like something on the intake system.
Thanks, I took a close look at the intake system and sure enough one of the hoses had become disconnected. Runs great now - no more whistling Dixie...