It's not that Hera's here to ask Sabine to quiet down her music. It's more that this level of volume tends to mean the Mandalorian has something heavy on her mind, and given the dangers of the holomap mission, she'd rather check in now than later, when it's too late.

Which is why she doesn't bother knocking, just kicks the door hard -- two dull thuds in quick succession -- and raises her voice in something more parade-ground yell than quiet inquiry.

"Sabine? Do you have a minute?"