Startup sounds

when OS11.1 (Gnome) starts I can hear a jingle, like most of OSes do.
Then, after a few moments, a second sound can be heard, and I cannot identify what triggers it.
Usually the only things that happen when I login are:

  • the laptop connects to the wi-fi network
  • guake starts
  • firefox starts

Anyone know where this sound come from and how can I disable it?
I’m getting mad trying to find out!