Computer engineers have dreamed of a machine that would translate speech into something that a vacuum tube or transistor could understand. Now at last, some promising hardware is being developed…. It is still a long way from the kind of science fiction computer that can understand sentences or long speeches. — Science News, March 4, 1967
That 1967 device knew the words one through nine. Earlier speech recognition devices sliced a word into segments and analyzed them for absolute loudness. But this machine, developed by Genung L. Clapper at IBM, identified the volume of a pitch segment compared with its neighbors to account for the variability of human speech. Today’s speech recognition goes much further, dividing words into distinct units of sound and syntax. The software decodes speech by applying pattern recognition and a statistical method called the hidden Markov model to the sounds. We rely on speech recognition to open an app to order groceries or to send a text to ask someone at home if we need more milk. Hello, Siri.