DtB: Ryuusei no Gemini Episode 8 – What Misaki heard
Playing the part where she listened to the recording again and again in a slower pace, I can figure out the words ‘anata dake ni kikoeru,’ more or less.
This roughly translates to ‘And to only you I will listen.’ This ties in with the assumption that the contractor who can see the future is Amber. I assume it was her saying this, and she was saying this to Hei.
Of course, this is all guesswork. But try playing the scene again. The words are relatively distinct.