Accessibility

Accessibility

Accessibility, in a general sense, means a system must be designed to be usable by an almost unlimited range of people, essentially anyone who desires to use it.

Design objectives in creating accessibility for users with disabilities are:

o   Minimize all barriers that make a system difficult, or impossible, to use.

o   Provide compatibility with installed accessibility utilities.

Types of Disabilities

Disabilities can be grouped into several broad categories: visual, hearing, physical movement, speech or language impairments, cognitive disorders, and seizure disorders.

o   Visual disabilities can range from slightly reduced visual acuity to total blindness.

o   Hearing disabilities range from an inability to detect certain sounds to total deafness.

o   Physical movement disabilities include difficulties in, or an inability to, perform certain physical tasks such as moving a mouse, pressing two keyboard keys simultaneously, or accurately striking a single keyboard key.

o   People with speech or language disabilities may find it difficult to read and write (as with dyslexia).

o   Cognitive disabilities include memory impairments and perceptual problems.

o   People with seizure disorders are sensitive to visual flash rates, certain rates triggering seizures.

Accessibility Design

o   Consider accessibility issues during system planning, design, and testing.

o   Provide compatibility with installed accessibility utilities.

o   Provide a customizable interface.

o   Follow standard Windows conventions.

o   Use standard Windows controls.

Visual Disabilities

Utilities:

o   Ensure compatibility with screen-review utilities.

o   Ensure compatibility with screen-enlargement utilities.

Screen components:

o   Include meaningful screen and window titles.

o   Provide associated captions or labels for all controls, objects, icons, and

o   graphics.

o   Including graphical menu choices.

o   Provide a textual summary for each statistical graphic.

o   Allow for screen element scalability.

o   Support system settings for high contrast for all user interface controls and client area content.

o   When a “high contrast” setting is established, hide any images drawn behind the text to maintain screen information legibility.

o   Avoid displaying or hiding information based on the movement of the pointer.

o   Exception: Unless it’s part of the standard interface (Example: ToolTips).

Keyboard:

o   Provide a complete keyboard interface.

o   Provide a logical order of screen navigation.

Color:

o   Use color as an enhancing design characteristic.

o   Provide a variety of color selections capable of producing a range of contrast

o   levels.

o   Create the color combinations based on the system colors for window components.

o  Do not define specific colors.

Hearing Disabilities

Provide captions or transcripts of important audio content.

Provide an option to display a visual cue for all audio alerts.

Provide an option to adjust the volume.

Use audio as an enhancing design characteristic.

Provide a spell-check or grammar-check utility.

Physical Movement Disabilities

Provide voice-input systems.

Provide a complete and simple keyboard interface.

Provide a simple mouse interface.

Provide on-screen keyboards.

Provide keyboard filters.

Speech or Language Disabilities

Provide a spell-check or grammar-check utility.

Limit the use of time-based interfaces.

Never briefly display critical feedback or messages and then automatically remove them.

Provide an option to permit the user to adjust the length of the time-out

Cognitive Disabilities

Permit modification and simplification of the interface.

Limit the use of time-based interfaces.

Do not briefly display critical feedback or messages and then automatically remove them.

Provide an option to permit the user to adjust the length of the time-out.

Seizure Disorders

Use elements that do not blink or flicker at rates between frequency ranges of 2 Hz and 55 Hz.

Minimize the area of the screen that is flashing.

Avoid flashing that has a high level of contrast between states.

Provide an option to enable users to slow down or disable screen flashing.

Documentation

Provide documentation on all accessible features.

Provide documentation in alternate formats.

Provide online documentation for people who have difficulty reading or handling printed material.

Testing

Test all aspects of accessibility as part of the normal system testing process.