Screen Readers
What is a screen reader?
A screen reader is a software application that enables people with severe visual impairments to use a computer.
Screen readers work closely with the computer’s Operating System (OS) to provide information about icons, menus, dialogue boxes, files and folders.
A screen reader provides access to the entire OS that it works with, including many common applications.
Below are some links to screen readers that can be downloaded for free.
www.screenreader.net
www.nvda-project.org
How does a screen reader relay information to the user?
There are two ways that a screen reader can provide feedback to the user:
A screen reader uses a Text-To-Speech (TTS) engine to translate on-screen information into speech, which can be heard through earphones or speakers. A TTS may be a software application that comes bundled with the screen reader, or it may be a hardware device that plugs into the computer. Originally, before computers had soundcards, screen readers always used hardware TTS devices, but now that soundcards come as standard on all computers many find that a software TTS is preferable.
In addition to speech feedback, screen readers are also capable of providing information in Braille. An external hardware device, known as a refreshable Braille display is needed for this. A refreshable Braille display contains one or more rows of cells. Each cell can be formed into the shape of a Braille character, a series of dots that are similar to domino dots in their layout. As the information on the computer screen changes, so does the Braille characters on the display change, providing refreshable information directly from the computer.
Whilst it is possible to use either format independently, Braille output is commonly used in conjunction with speech output.
How does a screen reader work?
Since the majority of screen reader users don’t use a mouse, all screen readers use a wide variety of keyboard commands to carry out different tasks. Tasks include reading part or whole of a document, navigating web pages, opening and closing files, editing and listening to music.
A visually impaired computer user will use a combination of screen reader commands and operating system commands to accomplish the many tasks a computer is capable of performing. All current operating systems have their own keyboard shortcuts, which are available to everyone not just screen reader users. An example of a Microsoft Windows keyboard shortcut is using the alt + A key combination to open the Favourites menu in Internet Explorer.
Each screen reader uses a different series of commands, so most people will tend to choose a screen reader and stick with it, as the task of learning a large number of new keyboard commands is considerable.