Seminar Page 2
There are a variety of audiences needing to use an accessible Web site. They include:
These are people who may rely on a screen reader (or software which reads content aloud) to access Web sites. Visual cues such as images, layout of data tables or multi-columns layouts may be unavailable to them without adding additional information within anHTML document.
Screen readers are used by users with severe visual impairment. They may be paired with Text only browsers such as Lynx in order to facilitate screen reader operation.
Some users may be using a text-only browser such as a PDA, cell phone Web viewer, or they may disable image downloading because of slow connections. Users outside the United States may only have access to the Internet via a text-only browser such as Lynx or a cell phone.
JAWS is one of the most commonly used screen reader programs. It not only reads Web sites, but reads all text within the Windows system (application menus, document text, help screens, and so forth).
These people may use a visual browser but may need to enlarge text or use special high-contrast font and color settings in order to access online information. It is important thatHTML markup NOT inadvertently disable zooming or the ability to adjust color/font settings.
See Ever Heard of Contrast? for details on low versus high contrast.
Low vision users need a mechanism to zoom content on a computer screen, sometimes to very large sizes. Zooming works well for vector-based text and PNG. graphics, but causes pixellation for bitmapped images such as GIF and JPEG.
Many users with special visual needs may implement custom stylesheets or plugins to override formatting specified on the page. The adjustments differ from person to person and can include:
Users, particularly older users, may wish to zoom the text of a particular Web site because of small text size. In addition, some color combinations with bright colors and fonts are harder to read for all users.
People who may be photo sensitive (e.g. migraine sufferers) or work in poor lighting conditions may need to adjust their browser views and colors.
Slightly under 10% of all men suffer some form of color blindness, so this audience is actually very widespread. Color blind users may not be able to distinguish certain color cues, especially red versus green. It is important that content not rely only on changes in color, but have alternate cues available to color blind users.
Note: Screen readers also cannot spell out color differences, so alternatives to color changes must also be included for users with severe visual impairment.
Because most color blind people can function adequately in most situations without special accommodations, this audience is not one that is "visible." It is only when pure color coding is used that color blind users have difficulties with online material.
A hearing impaired person can see all the visual information in a Web site, but will not be able to hear any audio content. Audio information should be presented in an alternative textual format or be captioned for hearing-impaired users.
Some users may not have access to audio on their computers. It is very common to mute audio in public labs or common work areas and other users may have trouble configuring their audio options.
Users with limited mobility may need to rely less on on a mouse and more on keyboards, special trackballs and input devices such as speech recognition software. Use of floating menus or small icons can be problematic for these users.
Mouse alternatives include special trackballs, "sip and puff" systems, joysticks controlled by the teeth, eye tracking devices, speech recognition input or keyboard only systems.
Users with carpal tunnel syndrome or who sprain or break an arm, elbow or limb will need to rely on mouse alternates for the duration of their injury. In addition, many users find moving and holding down a mouse button frustrating, especially on an unfamiliar computer or laptop.
Users with cognitive impairments may have difficulties processing certain types of information. At Penn State, these users would include users with various learning disabilities (the largest set of students registered with the Office of Disability Services).
Experts generally recommend a consistent, simple interface in order to help users with some cognitive impairements more easily process online information. Specific recommendations include:
Place universal navigational schemes in a consistent location on all Web sites.
Make sure a Home link is included on as many pages as possible. Do not rely on a clickable logo alone to act as a home link - many people do not know that convention. Some research also indicates that most users expext the Home link to be in the upper left portion of a screen or menu.
Use shorter chunks of text with plain language. Shorter text also helps many users who skim information on a Web rather than reading it.
In some cases, using graphical buttons can help some users, but make sure these buttons also include text labels for non U.S. vistors and ALT text for screen readers.
Avoid automatic background audio as it can be distracting for some users.
- Change CSS styles to add left and right margins and increase line spacing to increase readability.
Some users, including those with certain types of epilepsy and migraines, may be susceptible to attacks or "episodes" depending on how "loud" the visual presentation is. In particular:
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