Car Makes whining noise

I have a 1998 Mazda Millenia with 130k miles. About 2 weeks ago it started making a fairly high-pitched whining sound that seems to be coming from under the hood. It drives fine, but I am concerned and wonder what could be causing this noise.

Simplest cause would be a belt, worst case power steering motor or ac (not an exhaustive list to be sure). If you do not feel comfortable finding the cause any reputable mechanic should have no trouble. It is a warning signal, “HEY CHECK ME OUT” so it is best to get it looked at to avoid roadside a picnic.

Is this Millenium (after all, it is just one car) one of the “type S” Millenia?
If the answer is yes, the whining noise could be from the supercharger.