Finding a voice

Computers have got much better at translation, voice recognition and speech synthesis, says Lane Greene. But they still don't understand the meaning of language I'm afraid I can't do that." With chilling calm, HAL 9000, the on-board computer in "2001: A Space Odyssey", refuses to open the doors to Dave Bowman, an astronaut who had ventured outside the ship. HAL's decision to turn on his human companion reflected a wave of fear about intelligent computers. When the film came out in 1968, computers that could have proper conversations with humans seemed nearly as far away as manned flight to Jupiter. Since then, humankind has progressed quite a lot farther with building machines that it can talk to, and that can respond with something resembling natural speech. Even so, communication remains difficult. If "2001" had been made to reflect the state of today's language technology, the conversation might have gone something like this: "Open the pod bay doors, Hal." "I'm sorry, Dave.