Speech style sheets

The aural properties allow you to control how a speech browser reads your page. Obviously, this helps blind or partially sighted people to use web pages. But there could be other uses. People also access the Internet on WAP phones (or other handheld devices for that matter). It is hard to to display much text and graphics on these devices, so speech browsers seem like a good idea. You might also see devices in cars so that drivers can find information on the Internet such as directions, traffic reports, or weather conditions.

So, what can you do?

You can set the volume. Why do you want to control volume? After all, users control the volume just like they control the volume when they listen to a CD. The main aim of the volume property is manage the relative volume of different bits of text in your page.

The speak property lets you control how your content is spoken. You can tell the browser to speak words with appropriate inflection and pronunciation, to spell out words or not to speak words at all.

The voice-family property sets the voice that you want to use for spoken text. This can be simply male or female or a specific voice. It works a bit like the font-family property. You can specify a single voice family, a list of alternative voice families separated by commas or a generic voice family.

You can manage how fast the voice speaks. Unless you specify otherwise, your content will be spoken at a rate of 180 to 200 words per minute. If you want to change this, use the speech-rate property.

You can also control tone and inflection. Use the pitch and pitch range properties to specify the average pitch of a speaking voice and range of inflection. Use the stress and richness properties to specify the amount of stress to give to parts of sentences and amount of brightness to give to the voice.

You can use pauses and audio cues to draw attention to certain passages of your document. Pauses control the pace of the presentation and draw a listener's attention when needed. The idea is that the browser handles punctuation, i.e it will know how to pauses for full stops, commas, and such like. You can set up any extra pauses with the pause-before, pause-after and pause properties. The cue-before, cue-after and cue properties specify a file to play before or after the browser speaks the tag.

If you want, you can add a background sound that you want to play with a tag. Use the play-during property to specify the sound.

Normally, you lay out pages in two-dimensions. Tags end up at a specific point on the page. The aural properties go one better because you get an extra dimension: you can get surround sound. Just like the clever audio systems that put sound above, below and around the listener (normal stereo just put sounds to the right and left of a listener). This does assume that the browser supports the properties.

You use the azimuth and elevation properties to get surround sound. The elevation property moves a sound up and down, the azimuth property moves it around the listener. You can assign these properties to any tag.

If you think of the listener as the center of a circle, the azimuth is the angle that the sound comes from. An azimuth of 0 degrees is directly in front of the listener; 90 degrees is to the right, 180 degrees is directly behind, and 270 degrees is to the left.

Once you set the azimuth, you set the elevation i.e the height of the sound. Again, this is an angle. An elevation of 0 degrees is on the listener's horizon. The maximum elevation is 90 degrees, directly overhead, and the minimum elevation is -90 degrees, directly below the listener.

In short, you can manipulate the sound of your document much like you would manipulate the display of your document in a conventional browser.