Signals: Cracking Codes

The final visit to the Blue Sky Café finds the hosts mystified. How does Maxine the waitress know what everyone wants if no one says anything? In Eastern France, Todd and Chantal discover towers relaying coded messages. Debra goes to Boston to observe reading machines and a voice-pattern recognition apparatus. She then goes to Berkeley to see a composer put together synthesized music. FILM INSERTS: Ways to say hello; signs are an international language.