A screen reader is a form of assistive technology (AT)[1] that renders text and image content as speech or braille output.
[3] Screen readers are software applications that attempt to convey what people with normal eyesight see on a display to their users via non-visual means, like text-to-speech,[4] sound icons,[5] or a braille device.
[9] SAID read the ASCII values of the display in a stream and spoke them through a large vocal track synthesizer the size of a suitcase, and it cost around $10,000.
In the 1980s, the Research Centre for the Education of the Visually Handicapped (RCEVH) at the University of Birmingham developed a Screen Reader for the BBC Micro and NEC Portable.
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.
[citation needed] 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.
[citation needed] One approach is to use available operating system messages and application object models to supplement accessibility APIs.
Web browsers, word processors, icons and windows and email programs are just some of the applications used successfully by screen reader users.
A relatively new development in the field is web-based applications like Spoken-Web that act as web portals, managing content like news updates, weather, science and business articles for visually-impaired or blind computer users.
[citation needed] 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".
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.