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CSS Speech Module

Last call for comments

1:48 pm on Aug 21, 2011 (gmt 0)

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joined:Oct 22, 2004
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CSS3 Speech module is now in last call state (Aug 18 , 2011) . Journey for making accessible web standards have come far from WCAG guidelines , SSML (Speech Synthesis Markup Language ) to CSS Speech

Here is the summary of what CSS Speech module provides.

CSS Speech standard specifies how to present the content in way which can be understood by speech synthesizers. Using CSS Speech module we can specify meta data like voice speed , pause information etc for content . This CSS information is used by User agents while rendering and producing final sound output for the content.

Typical usage for this would be

  • Screen readers
  • Machine to Human interaction ( e.g incase while you are driving car , car would read content for you online with appropriate pauses , breaks etc or your ebook reader will read the book , exactly the way it is read by humans)

    CSS Speech is based on concept of Aural Box Model for content to be rendered in speech form . It is a conterpart for visual box model for visual presentation of content.

    See the Visual box model for CSS and Aural Box Model below for similarities

    The analogy between Visual Box model and Aural Box model is as follows

    padding >>>> rest
    border >>>>> cue
    margin >>>>> pause

    Cue : Cue is small piece of sound which you can insert in between.

    Some of Properties and Characteristics which are available include

    Pause Properties


    Rest Properties


    Cue Properties


    Speaking Properties


    Mixing Properties


    Voice Characteristics


    The link below provides the complete summary for each of the above properties


    Sample code snippets

    voice-family: female;
    voice-balance: left;
    voice-pitch: high;
    voice-volume: -6dB;

    Explanation for Code snippet

    The user agent of end user will read the webpage paragraph with female voice , left channel etc.

    You can send your feedback for the last call to W3C , its open till Sept end.

  • 10:39 am on Aug 22, 2011 (gmt 0)

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    WebmasterWorld Senior Member 10+ Year Member

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    posts: 961
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    Hi benevolent001, thanks for highlighting this opportunity to get involved. And to reinforce the relationshp between coding for style and coding for accessibility note section 1.2 of the module:
    1.2. Relationship with CSS2.1
    The CSS Speech module is a re-work of the informative CSS2.1 Aural appendix, within which the "aural" media type was described, but also deprecated (in favor of the "speech" media type). Although the [CSS21] specification reserves the "speech" media type, it doesn't actually define the corresponding properties. This module describes the CSS properties that apply to the "speech" media type, and defines a new "box" model specifically for the aural dimension. [emphasis added]
    ... I really like the "illustration" of the aural box model in section 4 as well.

    Does anyone have any insight on expected developments in the non-visual world? I mean support for these properties is dreadful at the moment, and I was just dismayed to read
    Do not use display:none to visually hide content intended for screen readers [456bereastreet.com] earlier this month as it seems a huge step backwards. Are we really going to see css providing us with the tools to support non-visual users in the near future?