what is this noise [video]

[oz16us]

does anyone know what this noise is? It's really hard to make out on the video...you won't really hear it as you're more likely to hear the higher pitch of the belt turning...

but it sounds like a low frequency buzz kinda like an electrical surge...and it's continuous.

With the truck off, i don't hear it
Even with the AC off or on, it has no affect on that noise
When I start the truck, sometimes it comes on and sometimes it doesn't
But after some driving, the noise stays on.... and sometimes i can get it turn off temporary just by accelerating... then it disappears.
It's like a low electrical noise...not like a rough rumble or anything...
I hear it weather the truck is moving or not...so it's not a tire or suspection issue

It sorta sounds like a refrigerator buzzing loud at night...
any ideas?
thanks in advance

https://www.dropbox.com/s/6m6yhonbdt763mb/Video Jun 13, 8 16 19 PM.mov

 

[partsman48210]

Do you have an aftermarket stereo installed? Is it louder inside the cab or under the hood. I didn't watch your video because it wants me to download it

 

[oz16us]

actually, I just noticed yesterday as I was driving home... the PCV elbow that I recently replaced was somehow making that buzzing noise. It's sorta partially caved in. I only put it on 3 months ago, so I'm not sure what's up with it. What could be the reason why it's buzzing? is it that air is coming out? People online suggested I get it from auto zone and napa. I chose auto zone since it was $3 cheaper...

 

[01STrunner]

I get a similar noise every once in a blue moon which is impressive considering what I put my truck through. Pretty sure I know what your talking about with the low buzz almost like a fridge. I think mines coming from underneath the truck somewhere but not 100% sure...