Complex sentence: The front of the head featured a curved grille-which was pierced to allow the operator to breathe-fitted with parallel rows of blue neon tubes, which lit up in synchronization with Robby's' synthetic' speech.
Split into simpler sentences: The front of the head featured a curved grille which was pierced to allow the operator to breathe. The grille was fitted with parallel rows of blue neon tubes, which lit up in synchronization with Robby's' synthetic' speech.