91 Riv engine noise

The engine has a strange noise, it sounds like a bearing in one of the components within the serpentine belt but unable to trace the noise to one component. The air compressor pump, the power steering pump, the tensioner pulley, and the water pump have all been changed. The alternator has been checked and it is fine. I'm trying to find out if someone would know if it might be the belt or the tensioner itself. When the car is revved up the sound decipates. Any help would be greatly appreciated!!