[brcidd]

Sounds like a dry pulley bearing-- get under the hood and listen closely- could be idler or tensioner bearing- perhaps power steering pump or even a/c pulley bearing. Have someone hold rpm at critical noise making rpm and watch for vibration. Or sometime I use a 3 ft long rubber hose- to put next to each component and other end in my ear- works pretty good for isolating problem childs....should be able to feel the vibration with a stout rod as well.