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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">
<html lang=en>
<head>
<title>CSS3 Speech Module</title>
<meta content="text/html; charset=us-ascii" http-equiv=Content-Type>
<link href="../default.css" rel=stylesheet type="text/css">
<style type="text/css">
.prod { font-family: inherit; font-size: inherit }
pre.prod { white-space: pre-wrap; margin: 1em 0 1em 2em }
code { font-size: inherit; }
#box-shadow-samples td { background: white; color: black; }
</style>
<style type="text/css">
/*<![CDATA[*/
caption { text-align: left; font-weight: bold }
.note { font-style: italic }
.issue { color: maroon; font-style: italic }
div.example pre { color: green; margin-left: 2em }
dl { margin-left: 2em }
caption dfn { font-size: 120% }
*:target {
border: 1px dashed #66CC66;
}
/*]]>*/
</style>
<!-- link rel="stylesheet" type="text/css" href="http://www.w3.org/StyleSheets/TR/W3C-ED.css" -->
<link href="http://www.w3.org/StyleSheets/TR/W3C-ED" rel=stylesheet
type="text/css">
<body>
<div class=head> <!--begin-logo-->
<p><a href="http://www.w3.org/"><img alt=W3C height=48
src="http://www.w3.org/Icons/w3c_home" width=72></a> <!--end-logo-->
<h1 id=top>CSS3 Speech Module</h1>
<h2 class="no-num no-toc" id=longstatus-date>Editor's Draft 19 April 2011</h2>
<dl>
<dt>This version:
<dd><!--<a href="http://www.w3.org/TR/2011/WD-css3-speech-20110419">http://www.w3.org/TR/2011/ED-css3-speech-20110419</a>-->
<a
href="http://dev.w3.org/csswg/css3-speech">http://dev.w3.org/csswg/css3-speech</a>
<dt>Latest version:
<dd><a
href="http://www.w3.org/TR/css3-speech">http://www.w3.org/TR/css3-speech</a>
<dt>Previous versions:
<dd><a
href="http://www.w3.org/TR/2004/WD-css3-speech-20041216/">http://www.w3.org/TR/2004/WD-css3-speech-20041216/</a>
<dt id=editors-list>Editors:
<dd><a href="mailto:dsr@w3.org">Dave Raggett</a> (<a
href="http://www.w3.org/">W3C</a>/<a
href="http://www.canon.com/">Canon</a>)
<dd><a href="mailto:daniel@glazman.org">Daniel Glazman</a> (<a
href="http://www.disruptive-innovations.com/">Disruptive
Innovations</a>)
<dd><a href="mailto:csant@opera.com">Claudio Santambrogio</a> (<a
href="http://www.opera.com/">Opera Software</a>)
<dd><a href="mailto:dweck@daisy.org">Daniel Weck</a> (<a
href="http://www.daisy.org">DAISY Consortium</a>)
</dl>
<!--begin-copyright-->
<p class=copyright><a
href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright"
rel=license>Copyright</a> © 2011 <a
href="http://www.w3.org/"><acronym title="World Wide Web
Consortium">W3C</acronym></a><sup>®</sup> (<a
href="http://www.csail.mit.edu/"><acronym title="Massachusetts Institute
of Technology">MIT</acronym></a>, <a href="http://www.ercim.eu/"><acronym
title="European Research Consortium for Informatics and
Mathematics">ERCIM</acronym></a>, <a
href="http://www.keio.ac.jp/">Keio</a>), All Rights Reserved. W3C <a
href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>,
<a
href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a>
and <a
href="http://www.w3.org/Consortium/Legal/copyright-documents">document
use</a> rules apply.</p>
<!--end-copyright-->
<hr title="Separator for header">
</div>
<h2 class="no-num no-toc" id=abstract>Abstract</h2>
<p>CSS (Cascading Style Sheets) is a language for describing the rendering
of HTML and XML documents on screen, on paper, in speech, etc. CSS defines
aural properties that give control over rendering XML and HTML to speech.
This draft describes the text to speech properties proposed for CSS level
3, and is a re-work of the informative CSS2.1 Aural appendix <a
href="#CSS21" rel=biblioentry>[CSS21]<!--{{CSS21}}--></a>. These are
designed for match the model described in the Speech Synthesis Markup
Language (SSML) Version 1.0 <a href="#SPEECH-SYNTHESIS"
rel=biblioentry>[SPEECH-SYNTHESIS]<!--{{!SPEECH-SYNTHESIS}}--></a>.
<p>The CSS3 Speech Module is a community effort and if you would like to
help with implementation and driving the specification forward along the
W3C Recommendation track, please contact the editors.
<h2 class="no-num no-toc" id=status>Status of this document</h2>
<!--begin-status-->
<p>This is a public copy of the editors' draft. It is provided for
discussion only and may change at any moment. Its publication here does
not imply endorsement of its contents by W3C. Don't cite this document
other than as work in progress.
<p>The (<a
href="http://lists.w3.org/Archives/Public/www-style/">archived</a>) public
mailing list <a
href="mailto:www-style@w3.org?Subject=%5Bcss3-speech%5D%20PUT%20SUBJECT%20HERE">
www-style@w3.org</a> (see <a
href="http://www.w3.org/Mail/Request">instructions</a>) is preferred for
discussion of this specification. When sending e-mail, please put the text
“css3-speech” in the subject, preferably like this:
“[<!---->css3-speech<!---->] <em>…summary of
comment…</em>”
<p>This document was produced by the <a href="/Style/CSS/members">CSS
Working Group</a> (part of the <a href="/Style/">Style Activity</a>).
<p>This document was produced by a group operating under the <a
href="/Consortium/Patent-Policy-20040205/">5 February 2004 W3C Patent
Policy</a>. W3C maintains a <a href="/2004/01/pp-impl/32061/status"
rel=disclosure>public list of any patent disclosures</a> made in
connection with the deliverables of the group; that page also includes
instructions for disclosing a patent. An individual who has actual
knowledge of a patent which the individual believes contains <a
href="/Consortium/Patent-Policy-20040205/#def-essential">Essential
Claim(s)</a> must disclose the information in accordance with <a
href="/Consortium/Patent-Policy-20040205/#sec-Disclosure">section 6 of the
W3C Patent Policy</a>.</p>
<!--end-status-->
<hr>
<p>This document is a draft of one of the "modules" for the upcoming CSS3
specification.
<p>This document has been developed in cooperation with the <a
href="/Voice/Group/">Voice Browser working group</a> (<a
href="http://cgi.w3.org/MemberAccess/AccessRequest">W3C Members only</a>).
<p> </p>
<!-- p>The following features are judged "at risk" and may be dropped at the
end of the CR period,
especially if there has not been enough interest from implementers:
<ul>
</ul>
</p -->
<!-- li><a href="#issue-mark">mark</a></li -->
<p>The following issues need to be discussed and require working group
resolutions:
<ul>
<li><a href="#issue-phonemes">‘<code
class=property>phonemes</code>’ property breaks principle of
content/presentation separation</a>
<li><a href="#issue-speakability-name">‘<code
class=property>speakability</code>’ not an ideal property name
?</a>
<li><a href="#issue-lists">handling of list styles, numbered items</a>
</ul>
<!-- li><a href="#issue-voice-cues-volume">audio cues volume level relative to voice-volume</a></li -->
<!-- li><a href="#issue-speak_none">speak:none</a></li -->
<p>The CSS WG maintains an <a
href="http://www.w3.org/Style/CSS/Tracker/products/29">issues list</a> for
this module.
<h2 class="no-num no-toc" id=contents>Table of contents</h2>
<!--begin-toc-->
<ul class=toc>
<li><a href="#dependencies"><span class=secno>1. </span>Dependencies on
other modules</a>
<li><a href="#introduction"><span class=secno>2. </span>Introduction</a>
<li><a href="#aural-model"><span class=secno>3. </span>The aural "box"
model</a>
<li><a href="#mixing-props"><span class=secno>4. </span>Mixing properties:
‘<code class=property>voice-volume</code>’ and ‘<code
class=property>voice-balance</code>’</a>
<li><a href="#speaking-props"><span class=secno>5. </span>Speaking
properties: ‘<code class=property>speakability</code>’,
‘<code class=property>speak</code>’</a>
<li><a href="#pause-props"><span class=secno>6. </span>Pause properties:
‘<code class=property>pause-before</code>’, ‘<code
class=property>pause-after</code>’ and ‘<code
class=property>pause</code>’
<!-- a href="#collapsing">collapsing pauses</a --> </a>
<ul class=toc>
<li><a href="#collapsing"><span class=secno>6.1. </span>Collapsing
pauses</a>
</ul>
<li><a href="#rest-props"><span class=secno>7. </span>Rest properties:
‘<code class=property>rest-before</code>’, ‘<code
class=property>rest-after</code>’ and ‘<code
class=property>rest</code>’</a>
<li><a href="#cue-props"><span class=secno>8. </span>Cue properties:
‘<code class=property>cue-before</code>’, ‘<code
class=property>cue-after</code>’ and ‘<code
class=property>cue</code>’</a>
<li><a href="#voice-char-props"><span class=secno>9. </span>Voice
characteristic properties: ‘<code
class=property>voice-family</code>’, ‘<code
class=property>voice-rate</code>’, ‘<code
class=property>voice-pitch</code>’, ‘<code
class=property>voice-pitch-range</code>’ and ‘<code
class=property>voice-stress</code>’</a>
<li><a href="#duration-props"><span class=secno>10. </span>Duration
property: ‘<code class=property>voice-duration</code>’</a>
<li><a href="#phonetic-props"><span class=secno>11. </span>Phonetics:
‘<code class=property>phonemes</code>’ and ‘<code
class=css>@phonetic-alphabet</code>’</a>
<ul class=toc>
<li><a href="#phonetic-alphabet"><span class=secno>11.1.
</span>@phonetic-alphabet</a>
</ul>
<li><a href="#content"><span class=secno>12. </span>Inserted and replaced
content</a>
<li class=no-num><a href="#profiles">Appendix A — Profiles</a>
<li class=no-num><a href="#property-index">Appendix B — Property
index</a>
<li class=no-num><a href="#index">Appendix C — Index</a>
<li class=no-num><a href="#definitions">Appendix D — Definitions</a>
<ul class=toc>
<li class=no-num><a href="#glossary">Glossary</a>
<li class=no-num><a href="#conformance">Conformance</a>
<li class=no-num><a href="#exit">CR exit criteria</a>
</ul>
<li class=no-num><a href="#acks">Appendix E — Acknowledgements</a>
<li class=no-num><a href="#changes">Appendix F — Changes from
previous draft</a>
<li class=no-num><a href="#references">Appendix G — References</a>
<ul class=toc>
<li class=no-num><a href="#normative-references">Normative
references</a>
<li class=no-num><a href="#other-references">Other references</a>
</ul>
</ul>
<!--end-toc-->
<hr>
<h2 id=dependencies><span class=secno>1. </span>Dependencies on other
modules</h2>
<p>This CSS3 module depends on the following other CSS3 modules:
<ul>
<li>Values and Units <a href="#CSS3VAL"
rel=biblioentry>[CSS3VAL]<!--{{!CSS3VAL}}--></a>
<li>The box model <a href="#CSS3BOX"
rel=biblioentry>[CSS3BOX]<!--{{!CSS3BOX}}--></a>
</ul>
<p>It has non-normative (informative) references to the following other
CSS3 modules:
<ul>
<li>Cascade and Inheritance <a href="#CSS3CASCADE"
rel=biblioentry>[CSS3CASCADE]<!--{{CSS3CASCADE}}--></a>
<li>Generated and Replaced Content <a href="#CSS3GENCON"
rel=biblioentry>[CSS3GENCON]<!--{{CSS3GENCON}}--></a>
<li>Syntax <a href="#CSS3SYN"
rel=biblioentry>[CSS3SYN]<!--{{CSS3SYN}}--></a></li>
<!-- li>Tables [[CSS3TBL]]</li -->
<!-- li>Selectors [[SELECT]]</li -->
</ul>
<h2 id=introduction><span class=secno>2. </span>Introduction</h2>
<p>The speech rendering of a document, already commonly used by the blind
and print-impaired communities, combines speech synthesis and "auditory
icons". Often such aural presentation occurs by converting the document to
plain text and feeding this to a <dfn id=screen-reader>screen reader</dfn>
— software or hardware that simply reads all the characters on the
screen. This results in less effective presentation than would be the case
if the document structure were retained. Style sheet properties for text
to speech may be used together with visual properties (mixed media) or as
an aural alternative to visual presentation.
<p>Besides the obvious accessibility advantages, there are other large
markets for listening to information, including in-car use, industrial and
medical documentation systems (intranets), home entertainment, and to help
users learning to read or who have difficulty reading.
<p>When using voice properties, the canvas consists of a two channel stereo
space and a temporal space (you can specify <a href="#cue-props">audio
cues</a> before and after synthetic speech). The CSS properties also allow
authors to vary the characteristics of synthetic speech (voice type,
frequency, inflection, etc.).
<div class=example>
<p>Examples:</p>
<pre>
h1, h2, h3, h4, h5, h6 {
voice-family: paul;
voice-stress: moderate;
cue-before: url(ping.au)
}
p.heidi { voice-balance: left; voice-family: female }
p.peter { voice-balance: right; voice-family: male }
p.goat { voice-volume: soft }
</pre>
<p>This will direct the speech synthesizer to speak headers in a voice (a
kind of "audio font") called "paul". Before speaking the headers, a sound
sample will be played from the given URL. Paragraphs with class "heidi"
will appear to come from the left (if the sound system is capable of
stereo), and paragraphs of class "peter" from the right. Paragraphs with
class "goat" will be played softly.</p>
</div>
<p class=note> Note that content creators may conditionally include CSS
properties authored specifically for user-agents with text to speech
capabilities (TTS), by specifying the "speech" media type via the
<code>media</code> attribute of the <code>link</code> element, or with the
<code>@media</code> at-rule, or within an <code>@import</code> statement
(the "aural" media type was deprecated in the informative CSS2.1 Aural
appendix <a href="#CSS21" rel=biblioentry>[CSS21]<!--{{CSS21}}--></a>).
When doing so, the styles authored within the scope of such conditional
statements are ignored by user-agents that do not support speech
synthesis.
<h2 id=aural-model><span class=secno>3. </span>The aural "box" model</h2>
<p>The formatting model of CSS for aural media is based on a sequence of
sounds and silences that appear in a nested model which is related to the
visual box model; however the aural canvas is one-dimensional, monolinear.
For compatibility with the visual box model, we will call it the <dfn
id=aural-box-model>aural "box" model</dfn>.
<p>The element is surrounded by, in this order, ‘<a
href="#rest"><code class=property>rest</code></a>’, ‘<a
href="#cue"><code class=property>cue</code></a>’ and ‘<a
href="#pause"><code class=property>pause</code></a>’ properties -
they can be thought of as aural equivalents to ‘<code
class=property>padding</code>’, ‘<code
class=property>border</code>’ and ‘<code
class=property>margin</code>’ respectively.
<p>It can be represented in the following way (including the equivalent
properties from the visual box model for clarification of relationships):
<p><img alt="A graph depicting the aural 'box' model." id=aural-box
src=aural-box.png>
<p>where <dfn id=ltelementgt><element></dfn> is the selected element
to which the properties from the CSS3 Speech Module apply.
<p class=note> Note that the ‘<code class=property>none</code>’
value of the ‘<a href="#display-def"><code
class=property>display</code></a>’ property (which is defined in the
CSS box model <a href="#CSS3BOX"
rel=biblioentry>[CSS3BOX]<!--{{!CSS3BOX}}--></a> and which applies to all
media types) influences the resolved value of the ‘<a
href="#speakability"><code class=property>speakability</code></a>’
property (defined within this CSS3 module) when the ‘<code
class=property>auto</code>’ value is specified for ‘<a
href="#speakability"><code class=property>speakability</code></a>’.
This is the only case whereby a property defined externally to this CSS3
module affects a characteristic specific to the aural dimension (i.e. has
an impact within the aural "box" model).
<h2 id=mixing-props><span class=secno>4. </span>Mixing properties:
‘<a href="#voice-volume"><code
class=property>voice-volume</code></a>’ and ‘<a
href="#voice-balance"><code class=property>voice-balance</code></a>’</h2>
<table class=propdef summary="name: syntax">
<tbody>
<tr>
<td>Name:
<td><dfn id=voice-volume>voice-volume</dfn>
<tr>
<td><em>Value:</em>
<td><non-negative number> | <percentage> | silent | x-soft |
soft | medium | loud | x-loud | inherit
<tr>
<td><em>Initial:</em>
<td>medium
<tr>
<td><em>Applies to:</em>
<td>all elements
<tr>
<td><em>Inherited:</em>
<td>yes
<tr>
<td><em>Percentages:</em>
<td>refer to inherited value
<tr>
<td><em>Media:</em>
<td>speech
</table>
<p>The ‘<a href="#voice-volume"><code
class=property>voice-volume</code></a>’ refers to the amplitude of
the waveform output by the speech synthesiser. This may be mixed with
other audio sources, influencing the perceived loudness of synthetic
speech relative to these sources.</p>
<!-- p>
‘<code class=property>voice-volume</code>’ does not apply to <a href
="#cue-props">audio cues</a> for which there is a separate means
to set loudness (absolute, or relative to ‘<code class=property>voice-volume</code>’).
<span class="issue" id="issue-voice-cues-volume">
ISSUE: shouldn't audio cues be subjected to the voice-volume,
so that an inaudible element gets its entire content (within the aural "box" model) muted as well ?
The rationale is that voice-volume:silent is largely equivalent to visibility:hidden,
which affects border, padding and spacing (i.e. the entire content with regards to the CSS "visual" box model).
The audio cues should therefore only be allowed to set their volume levels <em>relatively</em> to the inherited voice-volume, not with absolute values as these may incorrectly enable audio output when the voice-volume itself is muted.
</span>
</p -->
<p>Values have the following meanings:
<dl><!-- dt><strong>auto</strong></dt>
<dd>
Resolves to a computed value of ‘<code class=property>medium</code>’ when ‘<code class=property>visibility</code>’ is ‘<code class=property>visible</code>’ (see [[!CSS3BOX]]),
otherwise resolves to a computed value of ‘<code class=property>silent</code>’.
</dd -->
<dt><strong><non-negative number></strong>
<dd>An integer or floating point number in the range ‘<code
class=css>0</code>’ to ‘<code class=css>100</code>’.
‘<code class=css>0</code>’ represents silence (the
<em>minimum</em> level), and 100 corresponds to the <em>maximum</em>
level. The volume scale is linear amplitude.
<dt><strong><percentage></strong>
<dd> Only positive values are allowed. Computed values are calculated
relative to the inherited value, and are then clipped to the range
‘<code class=css>0</code>’ to ‘<code
class=css>100</code>’.
<p class=note> Note that a leading "+" sign does not denote an increment.
For example, +50% is equivalent to 50%, so the computed value equals the
inherited value times 0.5 (divided by 2), then clipped to [0,100].</p>
<dt><strong>silent</strong>, <strong>x-soft</strong>,
<strong>soft</strong>, <strong>medium</strong>, <strong>loud</strong>,
and <strong>x-loud</strong>
<dd>A sequence of monotonically non-decreasing volume levels. The value of
‘<code class=property>silent</code>’ is mapped to
‘<code class=css>0</code>’ and ‘<code
class=property>x-loud</code>’ is mapped to ‘<code
class=css>100</code>’. The mapping of other values to numerical
volume levels is implementation dependent and may vary from one speech
synthesizer to the next.
</dl>
<p>User agents should allow the level corresponding to ‘<code
class=css>100</code>’ to be set by the listener. No one setting is
universally applicable; suitable values depend on the equipment in use
(speakers, headphones), and the environment (in car, home theater,
library) and personal preferences.
<p class=note> Note that there is a difference between an element whose
‘<a href="#voice-volume"><code
class=property>voice-volume</code></a>’ property has a value of
‘<code class=property>silent</code>’, and an element whose
‘<a href="#speakability"><code
class=property>speakability</code></a>’ property has the value
‘<code class=property>none</code>’. The former takes up the
same time as if it had been spoken, including any pause before and after
the element, but no sound is generated (although descendants may override
the ‘<a href="#voice-volume"><code
class=property>voice-volume</code></a>’ value and may therefore
generate audio output). The latter requires no time and is not rendered in
the aural dimension
<!-- (including its descendants, which cannot override the inherited 'none' value). -->
(although descendants may override the ‘<a
href="#speakability"><code class=property>speakability</code></a>’
value and may therefore generate audio output).
<table class=propdef summary="name: syntax">
<tbody>
<tr>
<td>Name:
<td><dfn id=voice-balance>voice-balance</dfn>
<tr>
<td><em>Value:</em>
<td><number> | left | center | right | leftwards | rightwards |
inherit
<tr>
<td><em>Initial:</em>
<td>center
<tr>
<td><em>Applies to:</em>
<td>all elements
<tr>
<td><em>Inherited:</em>
<td>yes
<tr>
<td><em>Percentages:</em>
<td>N/A
<tr>
<td><em>Media:</em>
<td>speech
</table>
<p>The ‘<a href="#voice-balance"><code
class=property>voice-balance</code></a>’ property refers to the
balance between left and right channels, and presumes a two channel
(stereo) model that is widely supported on consumer audio equipment.
<p>Values have the following meanings:
<dl>
<dt><strong><number></strong>
<dd>An integer or floating point number between ‘<code
class=css>-100</code>’ and ‘<code
class=css>100</code>’. For ‘<code
class=css>-100</code>’ only the left channel is audible. Simarly
for ‘<code class=css>100</code>’ or ‘<code
class=css>+100</code>’ only the right channel is audible. For
‘<code class=css>0</code>’ both channels have the same level,
so that the speech appears to be coming from the center.
<dt><strong>left</strong>
<dd>Same as ‘<code class=css>-100</code>’.
<dt><strong>center</strong>
<dd>Same as ‘<code class=css>0</code>’.
<dt><strong>right</strong>
<dd>Same as ‘<code class=css>100</code>’ or ‘<code
class=css>+100</code>’.
<dt><strong>leftwards</strong>
<dd>Moves the sound to the left, relative to the inherited ‘<a
href="#voice-balance"><code
class=property>voice-balance</code></a>’. More precisely, subtract
20 from the inherited value and clip the resulting value to the range
‘<code class=css>-100</code>’ and ‘<code
class=css>100</code>’.
<dt><strong>rightwards</strong>
<dd>Moves the sound to the right, relative to the inherited ‘<a
href="#voice-balance"><code
class=property>voice-balance</code></a>’. More precisely, add 20 to
the inherited value and clip the resulting value to the range
‘<code class=css>-100</code>’ and ‘<code
class=css>100</code>’.
</dl>
<p>Many speech synthesizers only support a single channel. The ‘<a
href="#voice-balance"><code class=property>voice-balance</code></a>’
property can then be treated as part of a post synthesis mixing step. This
is where speech is mixed with other audio sources.</p>
<!-- p>Unlike ‘<code class=property>voice-volume</code>’, ‘<code class=property>voice-balance</code>’
<em>does</em> apply to <a href="#cue-props">audio cues</a>.</p -->
<h2 id=speaking-props><span class=secno>5. </span>Speaking properties:
‘<a href="#speakability"><code
class=property>speakability</code></a>’, ‘<a
href="#speak"><code class=property>speak</code></a>’</h2>
<!-- <p>An additional speech property, speak-header, is described in the
CSS module covering tables.</p> -->
<table class=propdef summary="name: syntax">
<tbody>
<tr>
<td>Name:
<td><dfn id=speakability>speakability</dfn>
<tr>
<td><em>Value:</em>
<td>auto | none | normal | inherit
<tr>
<td><em>Initial:</em>
<td>auto
<tr>
<td><em>Applies to:</em>
<td>all elements
<tr>
<td><em>Inherited:</em>
<td>yes
<tr>
<td><em>Percentages:</em>
<td>N/A
<tr>
<td><em>Media:</em>
<td>speech
</table>
<p class=issue id=issue-speakability-name> ISSUE: should the "speakability"
property be named differently ? e.g. "speaking"
<p>This property specifies whether text will be rendered aurally.
<p>Values have the following meanings:
<dl>
<dt><strong>auto</strong>
<dd> Resolves to a computed value of ‘<code
class=property>none</code>’ when ‘<a
href="#display-def"><code class=property>display</code></a>’ is
‘<code class=property>none</code>’ (see <a href="#CSS3BOX"
rel=biblioentry>[CSS3BOX]<!--{{!CSS3BOX}}--></a>), otherwise resolves to
a computed value of ‘<code class=property>auto</code>’ which
yields a used value of ‘<code class=property>normal</code>’.
<dt><strong>none</strong>
<dd> This value causes an element (including pauses, cues, rests and
actual content) to not be rendered (i.e., the element has no effect in
the aural dimension).
<p class=note> Note that any of the descendants of the affected element
are allowed to override this value, so they may actually take part in
the aural rendering. However, the pauses, cues, and rests of the
ancestor element remain "deactivated" in the aural dimension, and
therefore do not contribute to the <a href="#collapsing">collapsing of
pauses</a> or additive behavior of adjacent rests.</p>
<!--
Descendant elements do not get rendered either;
this behavior cannot be overridden by setting the 'speakability' property on the descendants.
-->
<dt><strong>normal</strong>
<dd> The element is rendered aurally.
</dl>
<p class=note> Note that although the ‘<code
class=property>none</code>’ value of the ‘<a
href="#display-def"><code class=property>display</code></a>’
property cannot be overridden by descendants of the affected element (see
<a href="#CSS3BOX" rel=biblioentry>[CSS3BOX]<!--{{!CSS3BOX}}--></a>), the
‘<code class=property>auto</code>’ value of ‘<a
href="#speakability"><code class=property>speakability</code></a>’
can however be overridden by descendants, using either of ‘<code
class=property>none</code>’ or ‘<code
class=property>normal</code>’. In the case of ‘<code
class=property>normal</code>’, this would result in descendants
being rendered in the aural dimension even though they would not be
rendered on the visual canvas.
<!-- To ensure that an element <em>and its descendants</em> do not get rendered in the aural dimension,
use the ‘<code class=property>none</code>’ value for the ‘<code class=property>speakability</code>’ property. -->
</p>
<!-- p class="note">
Note that the value of the ‘<code class=property>visibility</code>’ property (see [[!CSS3BOX]])
may affect the computed value of ‘<code class=property>voice-volume</code>’, but do not affect the ‘<code class=property>speakability</code>’ property.
</p -->
<table class=propdef summary="name: syntax">
<tbody>
<tr>
<td>Name:
<td><dfn id=speak>speak</dfn>
<tr>
<td><em>Value:</em>
<td>normal | spell-out | digits | literal-punctuation | no-punctuation |
inherit
<tr>
<td><em>Initial:</em>
<td>normal
<tr>
<td><em>Applies to:</em>
<td>all elements
<tr>
<td><em>Inherited:</em>
<td>yes
<tr>
<td><em>Percentages:</em>
<td>N/A
<tr>
<td><em>Media:</em>
<td>speech
</table>
<p>This property specifies in what manner text gets rendered aurally.
<p>Values have the following meanings:
<dl>
<dt><strong>normal</strong>
<dd>Uses language-dependent pronunciation rules for rendering an element
and its children. Punctuation is not to be spoken, but instead rendered
naturally as various pauses.
<dt><strong>spell-out</strong>
<dd>Spells the text one letter at a time (useful for acronyms and
abbreviations). In languages where accented characters are rare, it is
permitted to drop accents in favor of alternative unaccented spellings.
As as example, in English, the word "rôle" can also be written as
"role". A conforming implementation would thus be able to spell-out
"rôle" as "R O L E".
<dt><strong>digits</strong>
<dd>Speak numbers one digit at a time, for instance, "twelve" would be
spoken as "one two", and "31" as "three one".
<dt><strong>literal-punctuation</strong>
<dd>Similar to ‘<code class=property>normal</code>’ value, but
punctuation such as semicolons, braces, and so on are to be spoken
literally.
<dt><strong>no-punctuation</strong>
<dd>Similar to ‘<code class=property>normal</code>’ value but
punctuation is not to be spoken nor rendered as various pauses.
</dl>
<p>Speech synthesizers are knowledgeable about what is and what is not a
number. The ‘<a href="#speak"><code
class=property>speak</code></a>’ property gives authors the means to
control how the synthesizer renders the numbers it discovers in the source
text, and may be implemented as a preprocessing step before passing the
text to the speech synthesizer.
<h2 id=pause-props><span class=secno>6. </span>Pause properties: ‘<a
href="#pause-before"><code class=property>pause-before</code></a>’,
‘<a href="#pause-after"><code
class=property>pause-after</code></a>’ and ‘<a
href="#pause"><code class=property>pause</code></a>’
<!-- a href="#collapsing">collapsing pauses</a --></h2>
<table class=propdef summary="name: syntax">
<tbody>
<tr>
<td>Name:
<td><dfn id=pause-before>pause-before</dfn>
<tr>
<td><em>Value:</em>
<td><time> | none | x-weak | weak | medium | strong | x-strong |
inherit
<tr>
<td><em>Initial:</em>
<td>implementation dependent
<tr>
<td><em>Applies to:</em>
<td>all elements
<tr>
<td><em>Inherited:</em>
<td>no
<tr>
<td><em>Percentages:</em>
<td>N/A
<tr>
<td><em>Media:</em>
<td>speech
</table>
<p>
<table class=propdef summary="name: syntax">
<tbody>
<tr>
<td>Name:
<td><dfn id=pause-after>pause-after</dfn>
<tr>
<td><em>Value:</em>
<td><time> | none | x-weak | weak | medium | strong | x-strong |
inherit
<tr>
<td><em>Initial:</em>
<td>implementation dependent
<tr>
<td><em>Applies to:</em>
<td>all elements
<tr>
<td><em>Inherited:</em>
<td>no
<tr>
<td><em>Percentages:</em>
<td>N/A
<tr>
<td><em>Media:</em>
<td>speech
</table>
<p>These properties specify a pause or prosodic boundary to be observed
before (or after) an element or, if any ‘<a href="#cue-before"><code
class=property>cue-before</code></a>’ (or ‘<a
href="#cue-after"><code class=property>cue-after</code></a>’) is
specified, before (or after) these.
<p>Values have the following meanings:
<dl>
<dt><strong><time></strong>
<dd>Expresses the pause in absolute time units, as per the syntax of
"time" values in <a href="#CSS3VAL"
rel=biblioentry>[CSS3VAL]<!--{{!CSS3VAL}}--></a> (seconds and
milliseconds, e.g. "3s", "250ms"). Only positive values are allowed.
<dt><strong>none</strong>, <strong>x-weak</strong>, <strong>weak</strong>,
<strong>medium</strong>, <strong>strong</strong>, and
<strong>x-strong</strong>
<dd>These values may be used to indicate the prosodic strength of the
break in speech output. The synthesis processor may insert a pause as
part of its implementation of the prosodic break. The value "none"
indicates that no prosodic break boundary should be output, and can be
used to inhibit a prosodic break which the processor would otherwise
produce. The other values indicate monotonically non-decreasing
(conceptually increasing) break strength between elements. "x-weak" and
"x-strong" are mnemonics for "extra weak" and "extra strong",
respectively. The stronger boundaries are typically accompanied by
pauses. The breaks between paragraphs are typically much stronger than
the breaks between words within a sentence.
</dl>
<table class=propdef summary="name: syntax">
<tbody>
<tr>
<td>Name:
<td><dfn id=pause>pause</dfn>
<tr>
<td><em>Value:</em>
<td>[ <‘<a href="#pause-before"><code
class=property>pause-before</code></a>’> || <‘<a
href="#pause-after"><code
class=property>pause-after</code></a>’> ] | inherit
<tr>
<td><em>Initial:</em>
<td>implementation dependent
<tr>
<td><em>Applies to:</em>
<td>all elements
<tr>
<td><em>Inherited:</em>
<td>no
<tr>
<td><em>Percentages:</em>
<td>N/A
<tr>
<td><em>Media:</em>
<td>speech
</table>
<p>The ‘<a href="#pause"><code class=property>pause</code></a>’
property is a shorthand for setting ‘<a href="#pause-before"><code
class=property>pause-before</code></a>’ and ‘<a
href="#pause-after"><code class=property>pause-after</code></a>’. If
two values are given, the first value is ‘<a
href="#pause-before"><code class=property>pause-before</code></a>’
and the second is ‘<a href="#pause-after"><code
class=property>pause-after</code></a>’. If only one value is given,
it applies to both properties.
<div class=example>
<p>Examples:</p>
<pre>
h1 { pause: 20ms } /* pause-before: 20ms; pause-after: 20ms */
h2 { pause: 30ms 40ms } /* pause-before: 30ms; pause-after: 40ms */