This is kind of dumb, but what just happened?

Hello, i was on my chroomebook, and i only had 2 tabs open. which were a google search and a blocked website, when i heard a sound like hmh. like a sound a human would make, it sounded like it was on a google meet, but i didnt have a google meet open. i only have 1 window open, so it wasn't from anything else, im kinda creeped out, also my sound was pretty low, but it sounded louder than my sound. any idea what that was?