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Assistive Technology (AT)
Quality software development requires a solid understanding of user needs. To develop Section 508-compliant software, you need to understand the needs of users with disabilities. This includes a familiarity with how users with different disabilities interact with their computers and the types of assistive technology they use to enhance their experience.
Many strategies and assistive technologies enable users with disabilities to access electronic information. Following is a brief introduction to some of them. As you proceed through this course, you will learn more about how you can support assistive technologies in Flash.
AT for Users with Visual Disabilities
Users who are blind usually use a keyboard, rather than a mouse, to interact with the computer. They may also use a Braille display or screen reader to access information from the computer. Screen reader software, such as JAWS or Window-Eyes, converts computer text to speech and reads it out loud.
People who have a visual disability other than blindness may use screen magnification software, such as ZoomText or Magic, to enlarge the computer display or to adjust the contrast.
Strategies for Users with Hearing Disabilities and Speech Impairments
Users who are deaf rely on captioning or a transcript to access the audio portions of software applications. Users with a hearing disability other than deafness may use assistive hearing devices to amplify sound, or they may rely on an application's volume control.
Currently, speech impairments are unlikely to impede computer access, as few applications rely on voice input. However, voice input technologies are becoming more widespread, and although they can improve accessibility for users with mobility or dexterity impairments, it is important to remember that users with speech impairments may need an alternative way to access information.
AT for Users with Mobility Impairments
People with mobility impairments may not be able to manipulate a mouse or a standard keyboard. These individuals may use alternative input devices to control the computer. Such devices include speech recognition software, like Dragon NaturallySpeaking, which substitutes voice commands for keyboard and mouse input; and on-screen keyboards that are activated by pointing devices, hardware switches or eye gaze technology.
How ATs Work
Assistive technologies typically obtain information from an application (like Flash) through an application programming interface (API) such as Microsoft Active Accessibility (MSAA) and then convey that information to the user. Although MSAA recognizes and automatically conveys some types of information to the user, in most cases, Flash developers must perform specific steps to expose the information to MSAA so that it can be passed along to the user. Many of the accessibility techniques in this course are, simply put, techniques for ensuring that you expose the right information to AT.
Although this course focuses on one particular application framework — Flash — it is important to remember that assistive technology is more than an interface between Flash and the user. Using specialized but well-documented channels and techniques, AT interacts with the computer hardware, the operating system and other applications, as well as with the user. AT can monitor events generated by the system; it can monitor and intercept text and lines written through the computer's video card and sound played through the computer's sound card; and it can intercept keystrokes and act on them before they reach an application.
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