Analyzed the Pros and Cons, and Reminded Him in Time

Vincent could understand why Dave liked that long sword, but he did not expect to hear his voice!

Logically speaking, after the curtains were closed, the sound inside and outside the room should have been isolated. 

Vincent subconsciously moved his arm, and Monica, who was in a daze, instantly woke up. She hurriedly let go of Vincent's arm and sat back down on the sofa in a panic.

Vincent asked indifferently, "I think I heard Dave's voice just now. Isn't this room soundproof?"

Although Monica was only a staff member on the fifth floor, she was very familiar with the layout of Hell's Rose. She immediately said, "Although the room is soundproof, His Highness Dave is talking to those elves outside. Therefore, we can also hear the sounds coming from outside. There is a special sound transmission device on the windows of each private room. As long as you press the switch, your voice can be heard by everyone outside!"