source:https://www.soompi.com/2017/06/25/actress-kim-hyun-sing-ost-drama-ruler-master-mask/
Kim So Hyun will be lending her voice to the OST of her drama, “Ruler: Master of the Mask.”
A source from the MBC Wednesday-Thursday drama said, “The actress recently recorded her OST track, and it will be released next week.”
The title of Kim So Hyun’s song is, “Can’t You Hear My Heart” (literal title). As a ballad that reflects the feelings of Han Ga Eun, Kim So Hyun’s character, the growing tension in the instrumental will mix with the actress’s vocals to create an emotional song.
Kim So Hyun has showcased her singing in fan meetings and variety shows before, so it will be interesting to hear what kind of song she creates for the drama.