strange noises don't know the cause

I have a 2wd 1996 ford explorer sport in this past week it has been making some strange noises kinda shakey pitchy noises pretty inconsistent sound.The sound comes and goes whether I'm parked sitting at a stoplight or moving.It makes no difference if the ac/ heat is off or on. It sounds like the noise is coming from the altenator or that area. My battery is fine. when parked and I give it gas the noise increases. If anyone could give any suggestions about what might be causing this I'd appreciate it alot.

Maybe a bearing on one of your pulleys? Take a piece of rubber hose and hold one end to your ear and point the other end towards the pulleys. While someone accellerates the engine move from area to area. The hose will isolate the area the sound is coming from much better. Obviously pay attention to where you are sticking your hand.