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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"><html lang="en"><HEAD><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><TITLE>Aural style sheets</TITLE><link rel="stylesheet" href="style/default.css" type="text/css"><link rel="prev" href="ui.html"><link rel="next" href="sample.html"><link rel="contents" href="cover.html#minitoc"><link rel="CSS-properties" href="propidx.html" title="properties"><link rel="index" href="indexlist.html" title="index"></HEAD><BODY><div class="navbar" align="center"><p><a href="ui.html">previous</a> <a href="sample.html">next</a> <a href="cover.html#minitoc">contents</a> <a href="propidx.html">properties</a> <a href="indexlist.html">index</a> </div><hr class="navbar"><H1 align="center">19 <a name="aural">Aural style sheets</a></H1><div class="subtoc"><p><strong>Contents</strong> <ul class="toc"> <li class="tocline2"><a href="aural.html#q1" class="tocxref">19.1 Introduction to aural style sheets</a> <li class="tocline2"><a href="aural.html#volume-props" class="tocxref">19.2 Volume properties: <span class="propinst-volume">'volume'</span></a> <li class="tocline2"><a href="aural.html#speaking-props" class="tocxref">19.3 Speaking properties: <span class="propinst-speak">'speak'</span></a> <li class="tocline2"><a href="aural.html#pause-props" class="tocxref">19.4 Pause properties: <span class="propinst-pause-before">'pause-before'</span>, <span class="propinst-pause-after">'pause-after'</span>, and <span class="propinst-pause">'pause'</span></a> <li class="tocline2"><a href="aural.html#cue-props" class="tocxref">19.5 Cue properties: <span class="propinst-cue-before">'cue-before'</span>, <span class="propinst-cue-after">'cue-after'</span>, and <span class="propinst-cue">'cue'</span></a> <li class="tocline2"><a href="aural.html#mixing-props" class="tocxref">19.6 Mixing properties: <span class="propinst-play-during">'play-during'</span></a> <li class="tocline2"><a href="aural.html#spatial-props" class="tocxref">19.7 Spatial properties: <span class="propinst-azimuth">'azimuth'</span> and <span class="propinst-elevation">'elevation'</span></a> <li class="tocline2"><a href="aural.html#voice-char-props" class="tocxref">19.8 Voice characteristic properties: <span class="propinst-speech-rate">'speech-rate'</span>, <span class="propinst-voice-family">'voice-family'</span>, <span class="propinst-pitch">'pitch'</span>, <span class="propinst-pitch-range">'pitch-range'</span>, <span class="propinst-stress">'stress'</span>, and <span class="propinst-richness">'richness'</span></a> <li class="tocline2"><a href="aural.html#speech-props" class="tocxref">19.9 Speech properties: <span class="propinst-speak-punctuation">'speak-punctuation'</span> and <span class="propinst-speak-numeral">'speak-numeral'</span></a> </ul></div><H2><a name="q1">19.1 Introduction to aural style sheets</a></H2><p>The aural rendering of a document, already commonly used by theblind and print-impaired communities, combines speech synthesis and<a name="x0"><span class="index-def" title="auditory icon">"auditory icons."</span></a> Oftensuch aural presentation occurs by converting the document to plaintext and feeding this to a <a name="x1"><span class="index-def" title="screenreader"><dfn>screen reader</dfn></span></a> -- software or hardware thatsimply reads all the characters on the screen. This results in lesseffective presentation than would be the case if the documentstructure were retained. Style sheet properties for aural presentationmay be used together with visual properties (mixed media) or as anaural alternative to visual presentation.<p>Besides the obvious accessibility advantages, there are other largemarkets for listening to information, including in-car use, industrialand medical documentation systems (intranets), home entertainment, andto help users learning to read or who have difficulty reading.<p>When using aural properties, the <a name="x2"><span class="index-inst"title="canvas">canvas</span></a> consists of a three-dimensional physicalspace (sound surrounds) and a temporal space (one may specify soundsbefore, during, and after other sounds). The CSS properties alsoallow authors to vary the quality of synthesized speech (voice type,frequency, inflection, etc.).<div class="example"><P style="display:none">Example(s):</P><p><pre>H1, H2, H3, H4, H5, H6 { voice-family: paul; stress: 20; richness: 90; cue-before: url("ping.au")}P.heidi { azimuth: center-left }P.peter { azimuth: right }P.goat { volume: x-soft }</pre><p>This will direct the speech synthesizer to speak headers in a voice(a kind of "audio font") called "paul", on a flat tone, but in a veryrich voice. Before speaking the headers, a sound sample will be playedfrom the given URL. Paragraphs with class "heidi" will appear to comefrom front left (if the sound system is capable of spatial audio), andparagraphs of class "peter" from the right. Paragraphs with class"goat" will be very soft.</div><H2>19.2 <a name="volume-props">Volume properties</a>: <a href="aural.html#propdef-volume" class="noxref"><spanclass="propinst-volume">'volume'</span></a></H2><div class="propdef"><dl><dt><span class="index-def" title="'volume'"><a name="propdef-volume" class="propdef-title"><strong>'volume'</strong></a></span><dd><table class="propinfo" cellspacing=0 cellpadding=0><tr valign=baseline><td><em>Value:</em> <td><a href="syndata.html#value-def-number" class="noxref"><span class="value-inst-number"><number></span></a> | <a href="syndata.html#value-def-percentage" class="noxref"><span class="value-inst-percentage"><percentage></span></a> | silent | x-soft | soft | medium | loud |x-loud | <a href="cascade.html#value-def-inherit" class="noxref"><span class="value-inst-inherit">inherit</span></a><tr valign=baseline><td><em>Initial:</em> <td>medium<tr valign=baseline><td><em>Applies to:</em> <td>all elements<tr valign=baseline><td><em>Inherited:</em> <td>yes<tr valign=baseline><td><em>Percentages:</em> <td>refer to inherited value<tr valign=baseline><td><em>Media:</em> <td><a href="media.html#aural-media-group" class="noxref">aural</a></table></dl></div><P><a name="x4"><span class="index-def" title="volume">Volume</span></a> refers to themedian volume of the waveform. In other words, a highly inflectedvoice at a volume of 50 might peak well above that. The overall valuesare likely to be human adjustable for comfort, for example with aphysical volume control (which would increase both the 0 and 100values proportionately); what this property does is adjust the dynamicrange.<P>Values have the following meanings:</p><dl><dt><span class="index-inst" title="<number>"><a name="x5" href="syndata.html#value-def-number" class="noxref"><span class="value-inst-number"><strong><number></strong></span></a></span><dd>Any number between '0' and '100'.'0' represents the <em>minimum audible</em>volume level and 100 corresponds to the<em>maximum comfortable</em> level.<dt><span class="index-inst" title="<percentage>"><a name="x6" href="syndata.html#value-def-percentage" class="noxref"><span class="value-inst-percentage"><strong><percentage></strong></span></a></span><dd>Percentage values are calculated relative to the inherited value,and are then clipped to the range '0' to '100'.<dt><strong>silent</strong><dd>No sound at all. The value '0' does not meanthe same as 'silent'.<dt><strong>x-soft</strong><dd>Same as '0'.<dt><strong>soft</strong><dd>Same as '25'.<dt><strong>medium</strong><dd>Same as '50'.<dt><strong>loud</strong><dd>Same as '75'.<dt><strong>x-loud</strong><dd>Same as '100'.</dl><p>User agents should allow the values corresponding to '0' and '100'to be set by the listener. No one setting is universally applicable;suitable values depend on the equipment in use (speakers, headphones),the environment (in car, home theater, library) and personalpreferences. Some examples:</p><ul><li>A browser for in-car use has a setting for when there is lots ofbackground noise. '0' would map to a fairly high level and '100' to aquite high level. The speech is easily audible over the road noise butthe overall dynamic range is compressed. Cars with betterinsulation might allow a wider dynamic range.<li>Another speech browser is being used in an apartment, late atnight, or in a shared study room. '0' is set to a very quiet level and'100' to a fairly quiet level, too. As with the first example, thereis a low slope; the dynamic range is reduced. The actual volumes arelow here, whereas they were high in the first example.<li>In a quiet and isolated house, an expensive hi-fi home theatersetup. '0' is set fairly low and '100' to quite high; there is widedynamic range.</ul><p>The same author style sheet could be used in all cases, simply bymapping the '0' and '100' points suitably at the client side.<H2>19.3 <a name="speaking-props">Speaking properties</a>: <a href="aural.html#propdef-speak" class="noxref"><spanclass="propinst-speak">'speak'</span></a></H2><div class="propdef"><dl><dt><span class="index-def" title="'speak'"><a name="propdef-speak" class="propdef-title"><strong>'speak'</strong></a></span><dd><table class="propinfo" cellspacing=0 cellpadding=0><tr valign=baseline><td><em>Value:</em> <td>normal | none | spell-out | <a href="cascade.html#value-def-inherit" class="noxref"><span class="value-inst-inherit">inherit</span></a><tr valign=baseline><td><em>Initial:</em> <td>normal<tr valign=baseline><td><em>Applies to:</em> <td>all elements<tr valign=baseline><td><em>Inherited:</em> <td>yes<tr valign=baseline><td><em>Percentages:</em> <td>N/A<tr valign=baseline><td><em>Media:</em> <td><a href="media.html#aural-media-group" class="noxref">aural</a></table></dl></div><P>This property specifies whether text will be rendered aurally andif so, in what manner (somewhat analogous to the <a href="visuren.html#propdef-display" class="noxref"><spanclass="propinst-display">'display'</span></a> property). The possiblevalues are:<dl><dt><strong>none</strong></dt><dd>Suppresses aural rendering so that theelement requires no time to render. Note, however, thatdescendants may override this value and will be spoken. (Tobe sure to suppress rendering of anelement and its descendants, use the<a href="visuren.html#propdef-display" class="noxref"><span class="propinst-display">'display'</span></a> property).<dt><strong>normal</strong></dt><dd>Uses language-dependent pronunciation rules for renderingan element and its children.<dt><strong>spell-out</strong></dt><dd>Spells the text one letter at a time (useful for acronyms andabbreviations).</dl><p>Note the difference between an element whose <a href="aural.html#propdef-volume" class="noxref"><spanclass="propinst-volume">'volume'</span></a> property has a value of'silent' and an element whose <a href="aural.html#propdef-speak" class="noxref"><spanclass="propinst-speak">'speak'</span></a> property has the value 'none'.The former takes up the same time as if it had been spoken, includingany pause before and after the element, but no sound is generated. Thelatter requires no time and is not rendered (though its descendantsmay be).<H2>19.4 <a name="pause-props">Pause properties</a>: <a href="aural.html#propdef-pause-before" class="noxref"><spanclass="propinst-pause-before">'pause-before'</span></a>, <a href="aural.html#propdef-pause-after" class="noxref"><spanclass="propinst-pause-after">'pause-after'</span></a>, and <a href="aural.html#propdef-pause" class="noxref"><spanclass="propinst-pause">'pause'</span></a></H2><div class="propdef"><dl><dt><span class="index-def" title="'pause-before'"><a name="propdef-pause-before" class="propdef-title"><strong>'pause-before'</strong></a></span><dd><table class="propinfo" cellspacing=0 cellpadding=0><tr valign=baseline><td><em>Value:</em> <td><a href="syndata.html#value-def-time" class="noxref"><span class="value-inst-time"><time></span></a> | <a href="syndata.html#value-def-percentage" class="noxref"><span class="value-inst-percentage"><percentage></span></a> | <a href="cascade.html#value-def-inherit" class="noxref"><span class="value-inst-inherit">inherit</span></a><tr valign=baseline><td><em>Initial:</em> <td>depends on user agent<tr valign=baseline><td><em>Applies to:</em> <td>all elements<tr valign=baseline><td><em>Inherited:</em> <td>no<tr valign=baseline><td><em>Percentages:</em> <td>see prose<tr valign=baseline><td><em>Media:</em> <td><a href="media.html#aural-media-group" class="noxref">aural</a>⌨️ 快捷键说明
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