The ultrasound isn't nominally designed to harm hearing - the point they have for including it is spyware monitoring of "air gapped" devices. They seem to have turned it down a little - I remember ten years ago the ultrasound from my old computer was severe enough I could hear if a game of Dwarf Fortress had paused itself (a stupid thing it loves to do) despite it having sound disabled, the speaker muted, and the display window completely minimized out of sight. Well, either they turned it down or my ability to hear ultrasound is waning, but I still hear it when bringing the computer out of hibernation - it just seems more focused on transmitting some ID code and finishing. I assume it's part of the OS, or at least, I never found a visible sign of it.