Assistive Technology For Computer Output

Braille Printers

One means of providing access to people with severe visual impairments is to provide a Braille printer with the computer. Braille embossers are essentially printers that print in Braille. To use this type of printer, the user's computer must also have software that translates on-screen text into its corresponding Braille representation for printing. With the proper software, Braille printers can effectively translate text documents into Braille and provide a hard copy, thus giving users with severe visual impairments access to that text.

Although they are an excellent means to access text-based documents, Braille printers are limited in their effectiveness for computer access. They do not provide a user with access to non-text-based output such as images or video files. Braille printers can be and often are best used in conjunction with other computer output access options such as screen magnifying or screen reading software.

Screen Magnifying Software

Screen magnifying software provides visual access to computer output by allowing a user to enlarge a portion of the physical screen to a magnification level they can functionally see. This enlarged portion is then fit to the entire display. When in use, at any one time the user can only see the portion of the screen that appears in the magnified viewing window. To see a different part of the screen, the user moves the mouse to the desired section and the magnified display changes accordingly. Screen magnifying software is typically used by people with varying degrees of low vision, but not those who are not completely blind.

Screen magnifying software typically provides the user with numerous customizable options including display, magnification, and contrast options. Display options include the enlarged portion of the screen displayed on the entire screen, half screen, quarter screen, or in a virtual magnifying glass. Different users need different levels of magnification. Most screen magnifying programs provide magnification options in set intervals from 1.5x to 36x the standard computer display size. Most of these software packages also provide options to change the contrast between the background of the screen and images, icons, or letters. This helps to emphasize these aspects of a computer display, making them more legible to people with visual impairments.

Screen magnifying software works simultaneously with most other computer programs including screen reading software. This helps provide computer output access to all standard computer programs, making it a valuable tool for people with low vision. There are many screen magnifying software programs available commercially including ZoomText, Big Shot, and Dolphin. Most computers also include a built-in, scaled down version of commercial screen magnifying software. These screen magnifying programs work for short-term use, but have limited options that limit their effectiveness. 

Screen Reading Software

Screen reading software is software that provides computer access in an audio context to people who are blind or who have severe visual impairments. The rule of thumb for screen reader use is that if someone needs use a screen magnifier to magnify the screen greater then 6x the standard screen size, a screen reader would be more effective. Screen reading software reads any text on the computer aloud to the user. Not only does this software provide access to text such as word processing documents or web page text, but it also reads functional text to help the user navigate the computer. Functional text includes text such as icon names, menu bar words, embedded links and other selection options. When reading these options, the software indicates the type of text to help the user differentiate between functional text and standard text. For example when reading an embedded link, the screen reader will first say "link" so the user knows the upcoming words provide an opportunity to navigate to another screen. This makes screen reading software an effective tool both for reading text on a computer and navigating the computer.

Screen reading software is keyboard driven, meaning it is controlled through a series of easily memorized key combinations that even a person who cannot see a keyboard can replicate. For example, to activate a link or menu option, when the screen reader indicates one of these options, the user simply must press the enter key to activate that option. Screen reading software is also customizable to meet each user's needs. There are typically many options for customizing the voice used, reading speed, and tone.  Similar to other output access software, screen reading software can be used with an other application, including screen magnifiers.

Windows computers contain a built-in screen reader called Narrator, however Narrator is very limited in its effectiveness. Upon start-up Narrator warns the user that if the user relies on a screen reader for computer access, the user should get a better product. Two popular commercially available screen readers are JAWS and Window Eyes.  

Talking Word Processors

Talking word processors can be used as both input and output AT. In general, talking word processors read aloud the contents of word processing programs to users with severe visual impairments or blindness. This software can either read an entire word processing document or it can echo each letter, word, or sentence as the user types. As input AT, talking word processors provide audio feedback to keystrokes from a standard keyboard to help the user to identify what is being typed. This helps a user who cannot see the screen or keyboard to verify what is being typed. As an output technology, talking word processors read the contents of open word processing documents aloud to the user. This provides people with low vision access to previously-written word processing documents. Although this software utilizes text-to-speech technology, it only works with word processing documents. Unlike screen reading software, talking word processors cannot read text in web sites or other software programs, thus limiting their effectiveness as full computer access options.

Refreshable Braille Displays

Refreshable Braille displays provide access to onscreen text by immediately translating this text into a Braille representation that is accessed via a dynamic display. A refreshable Braille display consists eight-dot cells on a display that is attached to the bottom of a standard keyboard. Initially, each dot is recessed into the display. When a line of text is selected on the the screen, that line is produced in Braille on the refreshable display. To accomplish this, the proper dots in each cell (each cell represents one letter) are raised to create the Braille representation of the selected text on the computer screen. Selecting or moving to the next line of text on the screen results in the display changing to reflect that text in Braille. Due to the small size of the display (one line), only one line of text can be displayed at a time. Refreshable Braille displays require screen reading software to work properly. This software is what interacts with the display hardware to create the Braille representations. This type of technology is used primarily by people who are both blind and deaf and thus would not be able to access computer output using either the magnified screen of screen magnifying software or the audio output of screen reading software. Refreshable Braille displays are also commonly used by screen reader users who cannot use their screen readers in their work environment due to noise restrictions.  

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