Jason Mink, vertebrate exclusion specialist at Foothill-Sierra Pest Control had to remove a bat from inside a house. He videoed the bat as he took it down from where it was roosting. The bat appears to be making sounds to deter the action. The bat has its mouth wide open, not to bite, but to make these sounds you hear.
11 April 2018. Burson California.
Jason says the bat was in between a window and the screen on the second floor. “The customer thinks it was in the room and tried to get out the open window and they closed the window on it. I got him out by slowly coaxing him on to my hand and then took him outside.”
Thanks to Corky Quirk of Norcalbats for the ID. She says Mexican free-tails are an extremely common species and very vocal.