The sound of someone approaching - something even Madoka can't miss, as she's staring at the device - isn't enough to make her look up. It does seem to startle the girl a little, since she shivers as her hands are moving to press the right buttons, to set the entire thing up, but she's doing her best to trust the man. If Wei Wuxian says that he will keep her safe, then.. surely he'll do his best.

He's done his best to listen to her before, after all. To take her concerns seriously. That should mean that he'll also take her safety very seriously.

But while she can at least trust him enough to keep working while it sounds like he's dealing with one of the very agitated people...

.. it's a little harder to do so when she hears a totally unexpected sound.

Madoka immediately turns her head, staring at Wei Wuxian, her mouth hanging open.

(Is she assuming that he was the one who let it rip that loudly? She's staring like she's dumbstruck!)