Follow the Rhythm, Move About!

When the server was pushing a cart of beverages and refreshments, he realized that this private room had actually drawn the curtains.

A while back, there had been only one person, and he had said he wanted to listen to music, but now, the private room had drawn the curtains and the room was now in "sealed mode." That meant that the private room's roof was also sealed, so people outside couldn't hear what was happening inside, and the people inside would not be disturbed by any activity outside.

What is one person doing in the private room with sealed mode? Listening to music? With the curtains drawn and the room sealed, what music is he listening to?

The server looked at the side. There was no "Do Not Disturb" sign and the curtains were not drawn all the way, meaning that there was nothing secretive going on, so the purpose was to block off the noise from outside.