Severus catches her look, but doesn't comment. He's not going to invite questioning. Instead he continues to read; more numbers being offered. Like Potter's, he'll remember it - he can't not, really, his memory is too good - but he has no plans of contacting her (or anyone) anytime soon. How ridiculous.

"There's a music room." Of course there's a music room, why wouldn't a floating interdimensional prison have a music room. Briefly, he feels strung between wanting to laugh and wanting to murder someone. But his expression remains neutral. Thankfully.