Mouth slit

What ArcHivist Hegelia termed the mouth slit was the equivalent of the humanoid mouth seen on the faceplates of certain subspecies of Cybermen. (AUDIO: The Early Cybermen)

The Cybermen produced by Cybus Industries in Pete's World had mouth slits which gave off blue light whenever they spoke. (TV: Rise of the Cybermen et al.) Similar Cybermen appeared in N-Space, associated with the Cyber Legions. (GAME: Blood of the Cybermen, TV: A Good Man Goes to War et al.) Later Cybermen, associated with the Cyberiad, also retained this feature. (TV: Nightmare in Silver et al.)