The aural style properties allows for the control of spoken voice and other sound effects to be assigned to element objects so that as they are displayed, their content may be spoken or read out to the user. This then makes the World Wide Web more accessible to sight impaired users.
So far, not much of this capability has found its way into the currently available web browsers.
There are many issues that have not yet been addressed with this aspect of style sheets. For example, controlling multi-lingual spoken text and dates may be somewhat problematic. Certainly the locale that the browser is operating in may be used to select a national language variant for the spoken word.