The Voice in the Machine ─ Building Computers That Understand Speech

Stanley Kubrick's 1968 film 2001: A Space Odyssey famouslyfeatured HAL, a computer with the ability to hold lengthy conversations with his fellow spacetravelers. More than forty years later, we have advanced computer technology that Kubrick neverimagined, but we do not have computers that talk and understand speech as HAL did. Is it a failureof our technology that we have not gotten much further than an automated voice that tells us to"say or press 1"? Or is there something fundamental in human language and speech that wedo not yet understand deeply enough to be able to replicate in a computer? In The Voice inthe Machine, Roberto Pieraccini examines six decades of work in science and technology todevelop computers that can interact with humans using speech and the industry that has arisen aroundthe quest for these technologies. He shows that although the computers today that understand speechmay not have HAL's capacity for conversation, they have capabilities that make them usable in manyapplications today and are on a fast track of improvement and innovation. Pieraccini describes theevolution of speech recognition and speech understanding processes from waveform methods toartificial intelligence approaches to statistical learning and modeling of human speech based on arigorous mathematical model--specifically, Hidden Markov Models (HMM). He details the development ofdialog systems, the ability to produce speech, and the process of bringing talking machines to themarket. Finally, he asks a question that only the future can answer: will we end up with HAL-likecomputers or something completely unexpected?

Roberto Pieraccini, Director of ICSI, the International Computer Science Institute in Berkeley, California, has been active for more than thirty years in speech research and technology.