Under load, accelerating there is high pitched not very load ticking or tappety noise. The noise decreases in intensity as load decreases.

Check the serpentine belt.

jack vehicle up and rotate one wheel at a time to see if noise is present, let me know what you find

It may be worn out valve lifters that are inside the engine. If you have more than 6,000 miles on the oil, valve lifters could run noisier. Changing to a high mileage type of motor oil may quite down the valve lifters noise somewhat. Synthetic oil used during the summer months could make it noisier too. If you can hear the noise while driving the car, it is not normal. Upon acceleration, if it gets noisier, you will be needing a valve job in the not to distant future.

check condition of drive belt and check tension of the belt as it may be slipping under load at revs.

check the belt tensioner.

What year , make , model an engine size ? Intake manifold gaskets

I took my car to Keller's Auto Repair in Gettysburg PA, He specializes in Chryslers. I have 04 Cruiser with 2.4 Turbo that had the same whistle noise, and check engine light on. He found code P0301. The noise was caused by the #1 Cylinder injector O ring. Check them out on facebook. They will help you.

http://www.facebook.com/#!/pages/Kellers-Auto-Repair/158207620880499

When does this happen? When you're turning? When the car is cold? Under acceleration? I need more info before I can make any suggestions.

you could be low on transmission fluid check that and make sure it registering properly on the dipstick.

YOU SHOULD TRY A NEW OIL FILTER AND USE SYNTHETIC OIL AND SEE HOW THAT GOES