Buzzing vibration

I have developed some kind of medium pitched humming vibration in my motor area. I can still feel it when stopped so that eliminates tires or hubs. I thought it was the idler pulley so I replaced that but I can still feel it.
Could it be the harmonic balancer? Seems like it is similar to when the water pump started going South a couple of years ago.

best thing to do is simply remove the serpentine belt and run the motor for just a coupl minutes to see if the noise goes away with the belt off. If it does shut the car off and spin each pulley by hand and feel for roughness.