High pitched noise, mostly light throttle

Hello everyone. I own a 2001 toyota tundra, 4x4, 130k miles. I love the truck besides this one very annoying problem. Whenever I'm going 30-40mph, or 45-65mph (give or take a few mph on both speed ranges) and give and try to maintain speed, a high pitched noise occurs, it sounds a little bit like your windshield wiper sprayers going off but higher pitched, it is fairly loud too. It gets louder and higher pitched when i barely give it throttle.. the noise completely goes away when i let go of the throttle completely. Then when i get back on it to maintain speed again it does it again. If i keep the same throttle position but decrease my speed (going up a hill) the sound lowers in pitch, then completely goes away once i hit a lower mph. It is a very annoying problem. Another way i can describe the noise is a vacuum cleaner going on upstairs while your in the basement. But a higher pitched windshield wiper sprayers going off sounds like the best description. The noise doesn't go away when swaying the car left and right. Please give me some opinions guys. I can't feel anything weird or see a anything weird in relation to my rpms so i dont think its my tranny or diffs...the maintenance guy at my work says it could be coming from my cat converter.. who knows man... thanks guys!

 

Hard to tell from your description and not being able to hear the noise but my first guess would be a slipping serpentine belt and/or bad tensioner/idler pulley bearing.

 

I was thinking belt tensioner as well, or possibly drive shaft carrier bearing?

 

It turned out to be the pinion bearing in my diff. Thanks tho