This presentation provides an overview of how GNU/Linux can be accessed using braille and speech-based user interfaces, as commonly employed by people who are blind or vision-impaired. In doing so, a conceptual framework is offered through which the different approaches taken by free software projects in this field can be characterized and compared.
The underlying braille and speech output technologies that form the basis of the user interfaces to be described later, are first introduced. The principles, practical operation and limitations of braille display hardware built upon piezoelectric cell technology are discussed. The BRLTTY braille access daemon supplies the necessary supporting drivers. The various speech synthesis systems available under Linux are also described, concentrating on software implementations distributed under open-source licences, specifically Festival, Festival Lite and eSpeak. The respective features and limitations of these systems, for the purpose of supporting spoken user interfaces, are explained.
Having laid the necessary groundwork, attention is turned to the software that makes user interfaces provided by the operating system and by applications accessible through braille and speech-based interaction. The screen reading paradigm that has conventionally defined the role of access software can be exemplified by several projects which allow users to interact with the Linux console, including YASR, SpeakUP and BRLTTY (in console mode). On the other hand, the Emacspeak project exhibits an alternative approach, whereby the Emacs editor and its applications are extended, in Emacs Lisp, to create a highly customized, and effective, spoken interface.
Accessibility architectures which extend widget libraries to support alternative user interfaces combine elements of both of these approaches. Like conventional screen readers, they offer generic access to the user interface, but like Emacspeak, they can also take advantage to some extent of the underlying structure and semantics of the application. The Gnome accessibility architecture, also supported by OpenOffice.org and Mozilla, is such a framework. (Support for this architecture in Qt 4 and KDE is under development). Having explained the principles of the Gnome accessibility infrastructure and its application, in the Orca assistive technology, to creating braille and spoken interfaces, the distinct approaches so far described are compared. The benefits and importance of collaboration among the various accessibility-related projects which have emerged in the free software community are emphasized.
The presentation concludes with an assessment of important technical challenges for the free software community in advancing braille and speech-based interfaces, as well as in improving the accessibility of the GNU/Linux operating system and its applications. This discussion emphasizes the vital role played by developers, at both the system and application levels, in this process, pointing out the extent to which success from the user's perspective requires, and benefits from, cooperation among a diverse range of development projects.
Jason has been enthusiastically using GNU/Linux since 1998, with both braille and speech output. Following technical collaboration with Dave Mielke, the maintainer of BRLTTY, in which a driver was extended to support his braille display device, Jason finally shelved his old DOS machine and was able to use GNU/Linux exclusively.
Jason is an active participant in project mailing lists devoted to free software and accessibility. He has also contributed to documentation, participated in beta testing and helped to track down bugs, particularly in the Emacspeak, BRLTTY and Yasr projects.
Jason has been extensively involved in technical standard-setting activities related to accessibility for people with disabilities. From 2000 to 2004 he served as co-Chair of the Web Content Accessibility Guidelines working group of the World Wide Web Consortium (W3C). He has also participated in working groups that have enhanced the support for accessibility provided by a number of W3C technical specifications, such as HTML, CSS and SVG. Since 1998, he has contributed to technical committees of the Daisy Consortium, developing standards and DTD's for accessible electronic books.
In real life, Jason is a Ph.D. student in philosophy, devoting much of his time to writing about conceptual issues in contemporary analytic semantics.
References relevant to the presentation are available here as HTML, and here in PDF format.