IMS Guidelines for Developing
Accessible Learning Applications
version 1.0 white paper
5. Guidelines for Accessible Delivery of Text, Audio, Images, and Multimedia
Every person learns differently. At its best, online learning allows each user to interact with lesson material in his or her preferred way, relying on their individual strengths while discounting as much as possible their weaknesses. The principles of excellent software design call on developers to work in full knowledge of the range of human skills and limitations. Software designers of teaching materials and activities, in particular, must strive to achieve this high standard.
When a user has a disability, access to learning software may depend entirely on how flexibly that product can deliver its content. Some users may need only to modify the parameters in which media is presented; other users may require entirely different media. Developers who achieve the kind of flexibility that diversity requires will enhance the accessibility of their product.
At a minimum, developers should provide text representations for all media types. This baseline will help address access for many users. That said, it should be noted that users with learning disabilities benefit from graphical presentations. For this reason, the practice of providing text-only content as an alternative to inaccessible multimedia content may not be an effective solution for users with cognitive disabilities.
A number of resources that address flexible media delivery are currently available. The W3C's Web Accessibility Initiative provides accessibility guidelines for W3C technologies such as HTML, XML, SMIL, CSS & SVG. It also provides more general guidelines for web content accessibility, authoring tool accessibility, and user agent accessibility. More information links are available in the Appendix. Two other comprehensive guides are referenced here.
The National Center for the Dissemination of Disability Research publication, User-Friendly Materials and Alternate Formats provides information on implementing several formats and modes including:
- large print
- video and descriptive video
- internet/World Wide Web
The California Community Colleges have produced a comprehensive set of guidelines that offer alternative formats for presenting printed materials, Guidelines for Producing Instructional and Other Printed Materials in Alternate Media for Persons with Disabilities.
The California Community Colleges document provides a comprehensive resource for producing several types of alternative media including:
- tactile graphics
- large print
- electronic text
5.1 Common Types of Media Delivery and Associated Presentation Formats
When text is correctly structured and formatted, it can be the most flexible way to present content. To make distributed online learning accessible, developers of learning platforms must provide a means to render digital text in alternative formats.
Specifically, it should be possible to render text as:
- Visual information. Text can be displayed on computer screens or other electronic devices (e.g. personal digital assistants, cell phones, e-book readers).
- Audio information. Text can be translated into speech using recordings or via synthesized speech provided by a computer.
- Tactile information. Text can be displayed on refreshable Braille displays or printed using a Braille embosser.
Common text accessibility problems include:
- hard-coded fonts that prevent users from changing style, size, color.
- text presented with background images or poor contrast colors that hinder readability.
- text presented in an image format that screen readers and Braille displays cannot transform.
- multi-column formats (including some tables) that screen readers cannot process in the correct order.
Learning system developers may enhance the accessibility of text for all users by following these practices:
- Offer features that allow the user to customize fonts and backgrounds.
- Allow ATs to have access to the source code.
- Use validated XHTML.
Content creators or educators may enhance the accessibility of text for all users by following these practices:
- Choose text formats that offer the most accessibility (e.g. XHTML, plain text).
- Use true text, and not graphical representations of text.
- Structure the text appropriately, identifying headings and other structural elements.
- Use styles or stylesheets to provide a flexible display.
Audio elements can add to the general appeal of online learning materials while making them more accessible to those who are print-impaired learners, such as those with visual impairments or dyslexia. However, developers should provide alternatives to ensure that learners who are deaf or hard-of-hearing are not disadvantaged.
Common audio accessibility problems include:
- lack of captions and/or transcripts.
- poor sound quality.
- inability to control volume.
Learning system developers may enhance the accessibility of audio for all users by following these practices:
- Provide a means to include captions and/or transcripts.
- Provide volume controls.
- Provide visual equivalents to audio alerts (e.g. show a text alert on the screen whenever an error beep is played).
Content creators or educators may enhance the accessibility of audio for all users by following these practices:
- Provide transcripts or captions for all essential audio.
- Consider providing other forms such as ASL or captions with images.
- An authoring tool to add captions, subtitles, and audio descriptions to digital media is available free-of-charge for content creators and educators. This tool, MAGpie (Media Access Generator), is available from the National Center for Accessible Media (NCAM).
- CAST (the Center for Applied Special Technology) offers Tips on Presenting Alternatives to Sound.
- Proprietary software exists that allows authors to add sign language displayed using animated characters. One company developing this software is Vcom3D. They have created "SigningAvatars" that are able to render content in Signed English and Pidgin Signed English (and possibly ASL in the future). More information is available from the Signing Avatar website.
Images can provide essential information. But without text support, images are not accessible for users who are blind or have low-vision. Developers must provide users with a way to access visual information. Providing text identification, or alternative text, will also benefit users of text-only browsers, such as mobile phones. In addition to providing, developers should ensure that images are scalable, so that users can enlarge them for better clarity.
Common image accessibility problems include:
- Failure to provide alternate text.
- Poor image resolution that restricts the ability of low-vision users to enlarge images.
Learning system developers may image enhance the accessibility of images for all users by following these practices:
- Provide a means to include text alternatives of images.
- Provide a zoom feature.
Content creators or educators may enhance the accessibility of images for all users by following these practices:
- Provide text alternatives for images.
- Use SVG features that improve accessibility (see section 4.2.3).
- Use the highest practical resolution for bit-mapped graphics when use of SVG is not possible (e.g., photographs).
- The University of Toronto's Special Needs Opportunity Windows (SNOW) provides information on making images accessible.
- The W3C WAI Techniques for Web Content Accessibility Guidelines 1.0 section 2.1.1 provide alternatives to auditory and visual content.
- The Web Design Group's article on use of alt-text in HTML.
- WebAIM's tutorial illustrating the W3C Web Content Accessibility Guidelines 1.0 recommendation checkpoint for providing "equivalent alternatives to auditory and visual content" (including code examples).
- Scalable Vector Graphics (SVG) is a language used in XML to describe two-dimensional graphics. SVG 1.0 is recommended by W3C.
- Descriptions of the accessibility features of SVG
Multimedia is the combination of text, graphics, video, animation, and sound. Thus, a given piece of multimedia content combines the access needs of each media type represented. Multimedia can be useful for many groups of learners, since a multi-modal presentation of information can be easier to understand. In general, users benefit when alternatives are available for each media type.
Common multimedia accessibility problems include:
- digital videos without captions, transcripts or audio descriptions.
Learning system developers may enhance the accessibility of multimedia for all users by following these practices:
- Provide the means to include accessibility features, such as captions, transcripts, and audio descriptions, within the multimedia format provided by the application.
Content creators or educators may enhance the accessibility of multimedia for all users by following these practices:
- Follow all relevant suggestions for enhancing accessibility for text, audio and images, since multimedia can combine all of these elements.
- Provide audio description describing essential visual elements for video content.
- Consider the importance of the timing of media delivery when planning access features. For example, a "talking head" video may need only a stand-alone transcript of the audio, but a documentary including graphics and other important visuals may require captions in order to maintain the link between visuals and narration.
The WGBH National Center for Accessible Media's Rich Media Accessibility website provides information of a wide range of digital media formats, including:
- A tutorial on Creating Audio Descriptions for Rich Media
- A tutorial on Creating Captions for Rich Media