Preface

In the past decade, there has been an explosion in the creation and commercial deployment of voice user interfaces, especially for use over the telephone. Voice user interfaces (VUIs) use speech technology to provide callers with access to information, allow them to perform transactions, and support communications.

This proliferation is driven by a number of factors: customer dissatisfaction with touchtone interactions, a growing desire for mobile access, the need for enterprises to more effectively and inexpensively meet their customers' needs, and the development of speech technology that is finally robust and reliable enough to deliver effective and reliable interaction in well-defined domains.

At the beginning of this decade of growth (starting around 1994), the biggest obstacle that needed to be overcome was skepticism about the capabilities of the technology. Speech technology had been promised for decades and had disappointed many times. The enterprises that could potentially improve their customer service and save money, as well as the venture capital firms that could fund the early start-ups, needed proof points. Within a few years, many such proof points existed: Millions of phone calls every day were being handled successfully by speech technology. Although technology improvement will continue to play a key role in providing better experiences for end users, increased business value to enterprises, and new capabilities enabling new types of applications, it is no longer the key bottleneck to growth of the speech industry.

The biggest challenge now is the design of the user interface. There are too few practitioners who have the knowledge and skills to create all the systems needed and to advance our understanding as new technology enables new capabilities. Current practitioners come from a wide variety of backgrounds: speech technology, user interface design, cognitive psychology, linguistics, and software development. All these fields have contributed to our current level of understanding of voice user interface design. In fact, the field has benefited substantially from the diversity of influences. However, the need to pull together information from diverse fields has made it difficult to codify and teach the rationale for design.

In this book we aim to offer in one place much of the background information needed for practitioners to design specific applications and to contribute to the advance of the field. We try to take a principled approach to deriving best practices, with the hope that designers will then have a basis for approaching new design situations and new technologies.