Screen reader - Citizendia

A screen reader is a software application that attempts to identify and interpret what is being displayed on the screen. Application software is a subclass of Computer software that employs the capabilities of a computer directly and thoroughly to a task that the user wishes to perform This interpretation is then represented to the user with text-to-speech, sound icons, or a braille output. Speech synthesis is the artificial production of human speech. A refreshable Braille display or Braille terminal is an electro-mechanical device for displaying Braille characters usually by means of raising dots through holes Screen readers are a form of assistive technology (AT) potentially useful to people who are blind, visually impaired, or learning disabled, often in combination with other AT such as screen magnifiers. Assistive technology (AT is a generic term that includes assistive adaptive and rehabilitative devices for people with disabilities and includes the process used in selecting Blindness is the condition of lacking Visual perception due to Physiological or Neurological factors Visual impairment or vision impairment is Vision loss that constitutes a significant limitation of visual capability resulting from Disease, In the United States and Canada, the term learning disability (LD refers to a group of disorders that affect a broad range of academic and functional skills including See also Magnifying glass A screen magnifier is software that interfaces with a computer's graphical output to present enlarged screen content

A person's choice of screen reader is dictated by many factors, including platform, cost (even to upgrade a screen reader can cost hundreds of U. S. dollars), and the role of organizations like charities, schools, and employers. Screen reader choice is contentious: differing priorities and strong preferences are common.

Increasingly, screen readers are being bundled with operating system distributions. Recent versions of Microsoft Windows come with the rather basic Narrator, while Apple Mac OS X includes VoiceOver, a more feature-rich screen reader. Microsoft Corporation is an American multinational Computer technology Corporation, which rose to dominate the Home computer Microsoft Windows is a series of Software Operating systems and Graphical user interfaces produced by Microsoft. Narrator is a light-duty Screen reader utility packaged with Microsoft Windows 2000, Windows XP and Windows Vista. Apple Inc, ( formerly Apple Computer Inc, is an American Multinational corporation with a focus on designing and manufacturing Consumer electronics Mac OS X (mæk oʊ ɛs tɛn is a line of computer Operating systems developed marketed and sold by Apple Inc, the latest of which is pre-loaded on all currently VoiceOver is a feature built into Apple Inc 's Mac OS X operating system since version 10 The console-based Oralux Linux distribution ships with three screen-reading environments: Emacspeak, Yasr and Speakup. Oralux is an association whose objective is to foster digital accessibility using solutions based upon Free Software and open standards Linux (commonly pronounced ˈlɪnəks Emacspeak is a free Screen reader for Emacs which is written in C, Emacs Lisp and Tcl and developed principally by The open source GNOME desktop environment long included Gnopernicus and now includes Orca. A gnome is a Mythical creature characterized by its extremely small size and subterranean lifestyle Gnopernicus is a free GNOME desktop application that provides Assistive Technologies (AT for blind and Visually impaired users Orca is a open source flexible extensible Assistive technology for people with visual impairments

There are also open source screen readers, such as the Linux Screen Reader for GNOME and NonVisual Desktop Access for Windows. Open source is a development methodology which offers practical accessibility to a product's source (goods and knowledge NonVisual Desktop Access (NVDA is a free open source portable Screen reader for Microsoft Windows.

The most widely used screen readers^[1] are separate commercial products: JAWS from Freedom Scientific, Window-Eyes from GW Micro, and Hal from Dolphin Computer Access being prominent examples in the English-speaking market. JAWS (an acronym for Job Access With Speech) is a Screen reader, a software program for visually impaired users produced by the Blind and Low Vision Freedom Scientific is a Corporation which researches creates and sells technology intended for people who are blind or have low vision and those with learning Window-Eyes is a Screen reader that makes a Computer usable by someone who is blind or has low vision. Dolphin Computer Access is a British company that designs creates and sells Software for people who are blind or have vision and print impairments

1 Types of screen reader
2 Screen reader customization
3 Emulators
4 Verbosity
5 References
6 See also

Types of screen reader

CLI (text) screen readers

In early operating systems such as MS-DOS which employed a Command Line Interface (CLI), the screen display consisted of characters mapping directly to a screen buffer in memory and a cursor position. MS-DOS (short for M icro' s' oft D isk O perating S ystem is an Operating system commercialized by Microsoft. Input was by keyboard. All this information could therefore all be obtained from the system either by hooking the flow of information around the system and reading the screen buffer or by using a standard hardware output socket^[2] and communicating the results to the user. For the slang term meaning female prostitution see Prostitution. This was relatively easy to engineer.

In the 1980s, the Research Centre for the Education of the Visually Handicapped (RCEVH) at the University of Birmingham developed Screen Reader for the BBC Micro and NEC Portable. ^[3]

GUI screen readers

Off-screen models

With the arrival of graphical user interfaces (GUIs), the situation became more complicated. A GUI has characters and graphics drawn on the screen at particular positions, and as such there is no purely textual representation of the graphical contents of the display. Screen readers were therefore forced to employ new low-level techniques, gathering messages from the operating system and using these to build up an "off-screen model", a representation of the display in which the required text content is stored. An operating system (commonly abbreviated OS and O/S) is the software component of a Computer system that is responsible for the management and coordination

For example, the operating system might send messages to draw a command button and its caption. These messages are intercepted and used to construct the off-screen model. The user can switch between controls (such as buttons) available on the screen and the captions and control contents will be read aloud and/or shown on refreshable Braille display.

Screen readers can also communicate information on menus, controls, and other visual constructs to permit blind users to interact with these constructs. However, maintaining an off-screen model is a significant technical challenge: hooking the low-level messages and maintaining an accurate model are both difficult tasks.

Accessibility APIs

Operating system and application designers have attempted to address these problems by providing ways for screen readers to access the display contents without having to maintain an off-screen model. These involve the provision of alternative and accessible representations of what is being displayed on the screen accessed through an API. Existing APIs include:

Screen readers can query the operating system or application for what is currently being displayed and receive updates when the display changes. Assistive Technology Service Provider Interface ( AT-SPI) is a Toolkit -neutral way of providing Accessibility facilities in applications. IAccessible2 is a new Accessibility API for Microsoft Windows applications Microsoft Active Accessibility is a COM -based Technology designed to improve the way Accessibility aids work with applications running on Microsoft UI Automation (UIA is a Managed code Application programming interface exposing user interface controls for Test automation and Assistive For example, a screen reader can be told that the current focus is on a button and the button caption to be communicated to the user. This approach is considerably easier for screen readers, but fails when applications do not comply with the accessibility API: for example, Microsoft Word does not comply with the MSAA API, so screen readers must still maintain an off-screen model for Word or find another way to access its contents. Microsoft Word is Microsoft 's flagship word processing software. One approach is to use available operating system messages and application object models to supplement accessibility APIs: the Thunder screenreader operates without an off-screen model in this way.

Screen readers can be assumed to be able to access all display content that is not intrinsically inaccessible. Web browsers, word processors, icons and windows and email programs are just some of the applications used successfully by screen reader users. However, using a screen reader is, according to some users, considerably more difficult than using a GUI and many applications have specific problems resulting from the nature of the application (e. g. animations in Macromedia Flash) or failure to comply with accessibility standards for the platform (e. g. Microsoft Word and Active Accessibility).

Self-voicing applications

Some programs speak or make other sounds so that they can be used by blind people or people who cannot see the screen. These programs are termed self-voicing and can be a form of assistive technology if they are designed to remove the need to use a screen reader. A self-voicing application is an application that provides an aural interface without requiring a separate Screen reader. Assistive technology (AT is a generic term that includes assistive adaptive and rehabilitative devices for people with disabilities and includes the process used in selecting

Web-based screen readers

A relatively new development in the field is web-based applications like Talklets that use JavaScript to add text-to-speech functionality to web content. JavaScript is a Scripting language most often used for Client-side web development Speech synthesis is the artificial production of human speech. The primary audience for such applications is those who have difficulty reading because of learning disabilities or language barriers. Although functionality remains limited compared to equivalent desktop applications, the major benefit is to increase the accessibility of said websites when viewed on public machines where users do not have permission to install custom software, giving people greater 'freedom to roam'.

Screen reader customization

Not only do screen readers differ widely from each other, but most are highly configurable. For example, most screen readers allow the user to select whether most punctuation is announced or silently ignored. Some screen readers can be tailored to a particular application through scripting. "Scripting" redirects here For other uses see Script. One advantage of scripting is that it allows customizations to be shared among users, increasing accessibility for all. JAWS enjoys an active script-sharing community, for example. JAWS (an acronym for Job Access With Speech) is a Screen reader, a software program for visually impaired users produced by the Blind and Low Vision

Emulators

Fangs screen reader emulator - An open source Mozilla Firefox extension that simulates how a web page would look in JAWS. JAWS (an acronym for Job Access With Speech) is a Screen reader, a software program for visually impaired users produced by the Blind and Low Vision

Verbosity

Verbosity is a term used to describe a feature of screen reading software that support vision-impaired computer users. Speech verbosity controls enable users to choose how much speech feedback they wish to hear. Specifically, verbosity settings allow users to construct a mental model of web pages displayed on their computer screen. Based on verbosity settings, a screen-reading program informs users of certain formatting changes, such as when a frame or table begins and ends, where graphics have been inserted into the text, or when a list appears in the document.

Some screen reading programs also include language verbosity, which automatically detects verbosity settings related to speech output language. For example, if a user navigated to a website based in the United Kingdom, the text would be read with a British accent.

References

^ Theofanos, Mary Frances, and Redish, Janice (Ginny) (November-December 2003). "Guidelines for Accessible and Usable Web Sites: Observing Users Who Work With Screen Readers" (HTML). Self-published version. . Redish & Associates Retrieved on 2007-26-01.
^ Talking Terminals. BYTE, September 1982. Retrieved on September 7, 2006.
^ Paul Blenkhorn, "The RCEVH project on micro-computer systems and computer assisted learning", British Journal of Visual Impairment, 4/3, 101-103 (1986). Free HTML version at Visugate. See also Access to personal computers using speech synthesis. RNIB New Beacon No.76, May 1992. Retrieved on August 17, 2005.

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