The ears of Rarity twitched softly before she turned her head down, facing her sister's chest. Ever so careful and almost not believing what she heard, Rarity laid Sweetie back in her bed and discharged her horn as a while. That was done to eliminate the mistakes of their magical powers colliding in one way or the other. Then she lowered her own head to the chest again and let her ear hover above it a bit as she started to listen more carefully. Just hoping to hear that mysterious sound again.