rhythmic noise when idling
 

At a stop sign there is this rhythmic whoof whoof whoof panting sound that goes away when i give just a touch of gas to increase the rpm a hair.
It might be a loose belt? I looked down at the indicators - the three notches - and I could see all three but don't know if that is bad or good. It's a 2008 with 50K. I am willing to change the belt, but not if it is okay!
Maybe the panting sound is just normal, IDK because I am not the main driver. If that is the case, I'd love to hear about it!

Are you able to post a video/audio clip of the sound?

no, not for a while I think.