v Bell felt sure he had all the pieces needed to implement this insight and give his wife the ability to understand human speech. He had already developed a moving drum and solenoid (a metal core wrapped with wire) that could transform a human voice into a time-varying current of electricity. All he needed to do, he thought, was to break up this electrical signal into different frequency bands, as he had done previously with the harmonic telegraph, then render each of these harmonics visually -- by using multiple phonautographs. In June of 1875, while attempting to prepare this experiment, he accidentally connected the wire from the input solenoid back to another similar device. Now most processes are not reversible. Try unsmashing a teacup or speaking into a reading machine for the blind, which converts print into speech; it will not convert the speech back into print. But, unexpectedly, Bell's erstwhile microphone began to speak! Thus was the telephone discovered, or we should say, invented.

The device ultimately broke down the communication barrier of distance for the human race. Ironically, Bell's great invention also deepened the isolation of the deaf. The two methods of communication available to the deaf -- sign language and lipreading -- are not possible over the telephone.

He continued to experiment with a frequency-based phonautograph, but without a computer to analyze the rapidly time-varying harmonic bands, the information remained a bewildering array to a sighted deaf person. We now know that we can visually examine frequency-based pictures of speech (i.e., spectrograms) and understand the communication from the visual information alone; but the process is extremely difficult and slow. An MIT graduate course, Speech Spectrogram Reading, teaches precisely this skill. The purpose of the course is to give students insight into the spectral cues of salient speech events. For many years, the course's professor, Dr. Victor Zue, was the only person who could understand speech from spectrograms with any proficiency; several people have reportedly now mastered this skill. Computers, on the other hand, can readily handle spectral information, and we can build a cruqde but usable speech-recognition system using this type of acoustic information alone. So Bell was on the right track -- about a century too soon.

Ironically, another pioneer, Charles Babbage, had attempted to create that other prerequisite to automatic speech recognition -- the programmable computer -- about forty years earlier. Babbage built his computer, the analytical engine, entirely of mechanical parts; yet it was a true computer, with a stored program, a central processing unit, and memory store. Despite Babbage's exhaustive efforts, nineteenth-century machining technology could not build the machine. Like Bell, Babbage was about a century ahead of his time, and the analytical engine never ran.

Not until the 1940s, when fueled by the exigencies of war, were the first computers actually built: the Z-3 by Konrad Zuse in Nazi Germany, the Mark I by U.S. Navy Commander Howard Aiken, and the Robinson and Colossus computers by Alan Turing and his English colleagues. Turing's Bletchley group broke the German Enigma code and are credited with enabling the Royal Air Force to win the Battle of Britain and so withstand the Nazi war machine.