From a different world than the traditional browsing world comes a range of techniques that allows a developer to code for speech behaviours much easier than previously possible. Opera has early support for this. W3C is working on standards for combining speech and the ordinary graphical user interface.

Speech Recognition

Understanding natural speech is hard for a machine, sometimes almost impossible. One approach to make this easier is to train the machine to recognize the user's voice and speech patterns. The user will be told to speak some predetermined texts to make the machine accustomed to the user.

This is not practical for web pages, so another approach is used instead, namely explicit grammars of expected utterances. The grammars have two advantages. The machine has a dramatically higher chance of guessing what the user meant this way. Also by restricting the accepted values it is easier to make a sensible response to the now known possible values.

Text To Speech

The machine talks back. It is possible get fairly natural machine generated voices, but this is a trade-off with file size, resource use, and flexibility. The machine voices typically used for web pages would fool nobody, but they are still easy to understand. Text To Speech is fairly common by now, but Opera is as of yet the only browser offering styled text using CSS.

XHTML+Voice

The language or profile Opera uses to combine XHTML and Voice is called XHTML+Voice, or X+V for short. More than for normal XHTML pages, X+V design is primarily about interaction design. You create the storyboard for what the user can do and when. You can make simple web page enhancement, or you can craft elaborate Byzantine labyrinths for the user to get lost in, it is all up to you.

An X+V web page is a normal XHTML page with additional Voice forms in the head. These voice forms cover both speech recognition and text to speech markup. The interaction is event based, you use XML Events to describe what should be the consequences or handlers of different events. An event can for instance be when the page has loaded, the user clicks on a button, or says something the speech recognizer doesn't understand. The consequence can be a voice monolog or dialog with the user. This is turn can for instance trigger a script, reformat the page, or throw another event.

Getting started with X+V

Voice user tutorial

Testing, testing. One, two, three. How do I use this Voice thing?

X+V by Example

Can you say "Hello World"? I knew you could... Start making X+V pages

X+V in Style

After all, it isn't as much what you say as how you say it. Add styled speech to X+V.

X+V in Action

Do as I say, not as I do. Use X+V to voice-enable JavaScript

How to Add Voice Interactivity to Your Site

Practical experience of adding voice to a web site