The robotic voice was intended to obscure the normal human voice so as to avoid being tracked and recognized. It's a technique mostly used by many hackers and those who want to break the law or create fear, this type of style has been used by the professor in Money Heist to confused the police and now it was Pedro who was confused. He asked "Who are you? Tell me who you are" he demanded. Pedro's eyes were reddish because of the excessive weed he's been smoking, when he screamed little particles of saliva came out his mouth and he was shaking as if he was about to have a seizure.
The robotic voice came up again "I give you a choice, either you or your men. I can't save all thirty one man but I can save you and that little girl, I know you value that girl don't you?"
