Format Presented with a group of seven "mystery singers" that identified only by their occupation, a guest artist and a pair of contestants must attempt to eliminate bad singers from the selection without ever hearing them perform live, over the course of five rounds. They are also assisted with clues regarding singers' backgrounds, style of performance, and observations from a celebrity panel. At the end of a game, the last remaining mystery singer is revealed as either good or bad by means of a duet between them and one of the guest artists. If the last remaining mystery singer is good, the contestants win ; this is also applied to the winning bad singer selected by them.
Rounds Visual round •
First impression () :s1–5: The guest artist and contestants are given some time to observe and examine each mystery singer based on their appearance (s1–3) or
heart rate (s4–5).
Lip sync round •
Lip sync () :s1–3: Each mystery singer performs a lip sync to a song; good singers mime to a recording of their own, while bad singers mime to a
backing track by another vocalist.
Evidence round •
Test picture () :s1–3: The guest artist and contestants are presented with a video package containing possible clues by one of the mystery singers.
Rehearsal round •
Sound box () :s1–3: The guest artist and contestants are presented with video from a recording session by one of the mystery singers, but pitch-shifted to obscure their actual vocals.
Interrogation round •
Interrogation () :s1–3: The guest artist and contestants may ask questions to the remaining mystery singers. Good singers are required to give truthful responses, while the bad singers must lie. ==Production==