Well, to be fair he was imagining voices and people when Finn first found him. Right now he's well-rested, as well as possibly still under the effect of Finn's powers.

"I can hardly wait," he chuckles, voice soft. Not just because he honestly wants to hear them, but also because hearing them will mean he'll be back to normal, something he most certainly is looking forward to. He only hopes that the cure is as promising as everyone is making it out to be.