2001 chevy blazer 4.3l
 

I just noticed the other day that I have a loud humming sound coming from my engine area. Not sure what it could be. Only changes when I increase my speed. No change in sound when vehicle shifts, turns, slows down, stopped, ac on or off, heater on or off. It's a consistent humming sound, baffled. Only quiets down when I take off from a stop.. 🤔🤔🤔 any one got any ideas