“Yeah, I think we’d all like to know the answer to that question,” says Christina in a singsong voice. “What did he say to you?”

How does "singsong" voice sounds here? What is Christina's tone like in the context?

Question

“Yeah, I think we’d all like to know the answer to that question,” says Christina in a singsong voice. “What did he say to you?”

How does "singsong" voice sounds here? What is Christina's tone like in the context?

Answer

Hello,
I believe it means that she is lighthearted or happy, making the words rise and fall in level and tone, as if almost singing.
Hope that helps, 
Liz GB 🤓✌️