You open the door to Tsuyu's appartment and walk inside, it sound fairly silent, which either meant she was napping or eating... that's when suddenly, you hear a loud ribb-BUUUUUURRRRRRPPPP!!!! from the kitchen... so probably eating again.

Tsuyu: "Sorry, excuse me kero! Come on in."

She says calmly from the kitchen before you hear the noises of eating resume.