Hissing sound - video link

https://youtu.be/n7HX_3CuMZ4

This is my Gen 3 3SGE ruining my day after a day of replacing my snapped alternator belt (happened an hour drive away from home, right before a job interview) and AC Drive Belt. What's that hissing sound? Vacuum leak?

Edit: By hissing, I mean that dip**** whine it's making