Lydia does not reply, because her hand is pressing to her mouth to suppress her urge to giggle as she watches and listens to Cour and Cosette perform. Yes, no doubt who the culprit is, now.

She inches her chair closer to Gale's, giving the pair her attention, or at least most of it, because she leans against the tall young man and murmurs, "It's adorable, though."

They do have lovely voices, and clearly Lydia is delighted without being wide-eyed about it.