Estinien looks a bit taken aback at just how positive Jaskier's response is, even though he had meant it as both a compliment and encouragement. Dragons saw things much the same way Jaskier did with regards to music, which is significant validation, in Estiniens' perspective. But now that he's caused the reaction he doesn't really know what to do with it.

Especially when Jaskier asks him if he knows any of the songs. His eyes widen in surprise, suddenly put on the spot. He sort of does remember some of them, but what he didn't explain is that what constitutes as music to dragons is significantly different from what mankind enjoys.

"Ah..." He pulls back slightly, considering. "A dragon song is..." Weirdly enough, part of him doesn't actually want to disappoint, despite the fact that he is definitely going to. "...'Tis more of a call. A roar, physically, but with a timbre that extends into the... spiritual."

He realizes how ridiculous that makes it sound right after saying it, but he has no other words for it. There would be no way for a man to truly replicate it. At least, not normally.