2009 Chevrolet HHR • 115,000 miles

There is this high toned whirring noise that comes from under the hood when I accelerate. This happens when it is in park or when it is moving. I opened the hood to see what I could - and I am not sure if this is the issue - but there is what appears to be a stem just to the left of the dipstick - and the top of the step looks like a nipple that would support a very small hose attached to it. I did not however - see any loose or dangling hoses that might have come off it. I have enclosed a picture. I hope that is all it is. Any help would be greatly appreciated.
January 7, 2013.

Look around to see if there is a hanging hose with no home.

It looks and sounds like a vacuum leak


Well. I thank you for your reply, but it is not a vacuum hose as I learned today. I had stated in my original post - that I looked for dangling hoses, but that nipple has nothing on it in several other HHRs I looked at today. The problem - I learned today, is the transmission, or specifically - the Torque Converter. The noise got progressively worse today, and eventually made a loud racket, and then the worst "NO DRIVE". I do thank you for the prompt response though.

Jan 8, 2013.