The only way to make all the information displayed on screen available to people who cannot read text is to have it spoken. Without spoken output, the menus, channel and programme names, programme guide, pop-up warnings and other on-screen text will always remain largely inaccessible to users who are blind, have a print disability or cannot read the language displayed.
This section describes how to achieve the best spoken output what to speak, how much, when, and in what way. It deals only with spoken output of the equipment user interface. It does not cover speaking of subtitles or text embedded in the programme (e.g. News tickers or phone numbers shown on screen). Some of those issues are covered in the guidelines sections onLanguage translations, Subtitles for people who are deaf or hard of hearing and Text and graphics displayed within a programme.
The guidelines presented here assume that there is a visual user interface displaying programme information, menus, warnings, etc. As text and graphics. The spoken output will then consist largely of a spoken equivalent of this text and graphics. This is in line with a mainstreaming approach to design where the speaking facility is added to standard existing equipment which includes a standard visual display.
The basic aim of spoken output in this context should be to give blind or vision impaired users information that is equivalent to that received by sighted users. The requirement for equivalence means that it is not always necessary, or even desirable, to repeat the visual content verbatim, as visual content often relies to some extent on its presentation (e.g. Shape and position) to convey meaning. It is also unnecessary to give blind viewers more information than sighted viewers receive, unless the extra information is specifically required by the blind user. For example, when switching channels, if the visual user interface displays the new channel and programme names but not the start and end times, it is not necessary to add the start and end times to the spoken output.
However, there are some pieces of information that are not important to sighted users but essential or very helpful for blind users. Examples are the number of items in a menu, the ordinal number of the current item (e.g. This is the 3rd menu item) and whether a programme includes audio description. Information such as this should be spoken even if it is not explicitly included in the visual display.
The guidelines in this section are functional user requirements and it is recognised that meeting some of them may present considerable challenges in certain cases, even being technically impossible with some technologies. For example, if an internet connected TV provides access to third party services such as video on demand and social networking, the content and many aspects of the user interfaces may be defined elsewhere, by the providers of those service. The TV manufacturer may therefore have no direct control over the universal design of some parts of the TV user interface. In these cases, manufacturers may be able to work with third party service providers, feeding back customer requirements and specifying relevant universal design requirements wherever the technologies make it possible to meet them.
It should be noted that the International Electrotechnical Commission (IEC) is currently developing a standard for text to speech output of broadcast receivers under its Technical Committee TC 100. The work towards this standard originated from joint work carried out by DIGITALEUROPE and the European Disability Forum and the resulting IEC standard is likely to be supported and promoted internationally by both equipment manufacturers and end users as the standard for implementing spoken output. If this happens, it will supersede these guidelines. The IEC standard is likely to be published some time during 2012 or 2013.
As stated in the overall introduction to the guidelines, these recommendations are largely the result of a compilation and restructuring of information contained in existing resources. The key resources used for this section were:
- Digital Television Group (DTG) D-Book standards on text to speech
- Developer's Guide to Creating Talking Menus for Set-top Boxes and DVDs
- IEC TC 100 requirements on Text To Speech For Television
- INTECO, Digital Terrestrial Television Accessibility Recommendations
- World Blind Union (WBU), International User Requirements for Television Receiving Equipment
- UK Consumer Expert Group, Vulnerable Consumer Requirements for Digital TV Equipment
These and other resources are referenced in the bibliography.