Oh. OH.
I've never thought about singing in Parseltongue. And I don't know why because it's genius. I could love Harry as a rock-star even more than I love Yann Tiersen (and believe me, I love him very much) because of his hissing. I think that Severus agrees with me (even if he doesn't like Yann's music).
Brilliant, my dear. You made my day. Again.