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Privately Professor May explained more. Heart of the robot system is an ordinary cathode-ray oscillograph, an electronic device which, when voice modulations are converted into electrical impulses as in a telephone, makes a jagged up-and-down record of them. Since different voices are differently pitched the device is rigged to ignore absolute pitch but to respond to relative pitch variations which occur in sequence in certain word combinations as pronounced by most speakers. Different combinations of variations close different combinations of relay circuits, and each combination of circuits is hooked up to the appropriate wax cylinder which supplies the answer, or to the proper motor which moves the robot as directed. Thus Alpha may answer "Seven" when asked "How many days in the week?" but remains dumb if the question is phrased "A week has how many days?"
Alpha was not quite correct in giving its age as 14. Professor May, a clever free-lance experimenter in electronics who is now working on voice-operated safes for banks, conceived Alpha 14 years ago but did not endow the robot with its present versatility until last year. He says it is now foolproof although it has not always been so. Once it fired its pistol without warning, blasting the skin off the professor's arm from wrist to elbow. Another time it lowered its arm unexpectedly, struck an assistant on the shoulder, bruised him so badly that he was hospitalized.