1994 Geo Metro Howling, Whining noise from the engine

Noises problem
1994 Geo Metro Front Wheel Drive Automatic 46000 miles

There is a whining, howling noise at a fast idle and any higher RPM. It sound like it is coming from the passenger side of the engine. I changed the alternator and checked the water pump, turning it by hand with the belt off. I had the old alternator bench tested(after the fact) and its OK, no noisy bearings as I first thought. The noise starts after the car warms up for just a short minute. I can also hear the noise when I'm driving at slower speeds. There are no check engine light or any other lights on. With only 46,000 miles on the car why is it making this noise.