Stanley Kubrick's 1968 film 2001: A Space Odyssey famously featured HAL, a computer with the ability to hold lengthy conversations with his fellow space travelers. More than forty years later, we have advanced computer technology that Kubrick never imagined, but we do not have computers that talk and understand speech as HAL did. Is it a failure of 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 we do not yet understand deeply enough to be able to replicate in a computer? In The Voice in the Machine, Roberto Pieraccini examines six decades of work in science and technology to develop computers that can interact with humans using speech and the industry that has arisen around the quest for these technologies. He shows that although the computers today that understand speech may not have HAL's capacity for conversation, they have capabilities that make them usable in many applications today and are on a fast track of improvement and innovation. Pieraccini describes the evolution of speech recognition and speech understanding processes from waveform methods to artificial intelligence approaches to statistical learning and modeling of human speech based on a rigorous mathematical model--specifically, Hidden Markov Models (HMM). He details the development of dialog systems, the ability to produce speech, and the process of bringing talking machines to the market. Finally, he asks a question that only the future can answer: will we end up with HAL-like computers or something completely unexpected?

斯坦利-库布里克（Stanley Kubrick）1968年的电影《2001年：太空漫游》（2001: A Space Odyssey）中，有一个著名的HAL，一台有能力与他的太空旅行者同伴进行长时间对话的计算机。40多年后，我们拥有了库布里克从未想象过的先进计算机技术，但我们没有像HAL那样会说话和理解语言的计算机。除了自动语音告诉我们 "说或按1 "之外，我们还没有取得更多进展，这是我们技术的失败吗？还是人类语言和语音中存在一些基本的东西，而我们对这些东西的理解还不够深刻，无法在计算机中复制？在《机器中的声音》中，罗伯托-皮耶尔卡尼研究了六十年来科学和技术领域为开发能够用语音与人类互动的计算机所做的工作，以及围绕对这些技术的追求而产生的产业。他表明，尽管今天能够理解语音的计算机可能不具备HAL的对话能力，但它们所具备的能力使它们在今天的许多应用中都可以使用，而且正处于改进和创新的快车道。Pieraccini描述了语音识别和语音理解过程的演变，从波形方法到人工智能方法，再到基于严格的数学模型的人类语音的统计学习和建模--特别是隐马尔可夫模型（HMM）。他详细介绍了对话系统的发展，产生语音的能力，以及将说话机器推向市场的过程。最后，他提出了一个只有未来才能回答的问题：我们最终会拥有像HAL一样的计算机还是完全出乎意料的东西？