aural.html

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BLOCKQUOTE Q   { play-during: url("harp.wav") mix }
SPAN.quiet     { play-during: none }
</pre>
</div>

<H2>19.7 <a name="spatial-props">Spatial properties</a>: <a href="aural.html#propdef-azimuth" class="noxref"><span
class="propinst-azimuth">'azimuth'</span></a> and
<a href="aural.html#propdef-elevation" class="noxref"><span class="propinst-elevation">'elevation'</span></a>
</H2>

<p>Spatial audio is an important stylistic property for aural
presentation. It provides a natural way to tell several voices apart,
as in real life (people rarely all stand in the same spot in a
room). Stereo speakers produce a lateral sound stage. Binaural
headphones or the increasingly popular 5-speaker home theater setups
can generate full surround sound, and multi-speaker setups can create
a true three-dimensional sound stage. VRML 2.0 also includes spatial
audio, which implies that in time consumer-priced spatial audio
hardware will become more widely available.</p>

<div class="propdef">
<dl><dt>
<span class="index-def" title="'azimuth'"><a name="propdef-azimuth" class="propdef-title"><strong>'azimuth'</strong></a></span>
<dd>
<table class="propinfo" cellspacing=0 cellpadding=0>
<tr valign=baseline><td><em>Value:</em>&nbsp;&nbsp;<td><a href="syndata.html#value-def-angle" class="noxref"><span class="value-inst-angle">&lt;angle&gt;</span></a> | [[ left-side | far-left | left | center-left | center |
center-right | right | far-right | right-side ] || behind ] |
leftwards | rightwards | <a href="cascade.html#value-def-inherit" class="noxref"><span class="value-inst-inherit">inherit</span></a>
<tr valign=baseline><td><em>Initial:</em>&nbsp;&nbsp;<td>center
<tr valign=baseline><td><em>Applies to:</em>&nbsp;&nbsp;<td>all elements
<tr valign=baseline><td><em>Inherited:</em>&nbsp;&nbsp;<td>yes
<tr valign=baseline><td><em>Percentages:</em>&nbsp;&nbsp;<td>N/A
<tr valign=baseline><td><em>Media:</em>&nbsp;&nbsp;<td><a href="media.html#aural-media-group" class="noxref">aural</a>
</table>
</dl>
</div>


<P>Values have the following meanings:</p>

<dl>
<dt><span class="index-inst" title="&lt;angle&gt;"><a name="x22" href="syndata.html#value-def-angle" class="noxref"><span class="value-inst-angle"><strong>&lt;angle&gt;</strong></span></a></span>
<dd>Position is described in terms of an angle
within the range '-360deg' to '360deg'.
The value '0deg' means directly ahead in the center of the sound
stage.  '90deg' is to the right, '180deg' behind, and '270deg' (or,
equivalently and more conveniently, '-90deg') to the left.
<dt><strong>left-side</strong>
<dd>Same as '270deg'. With 'behind', '270deg'.
<dt><strong>far-left</strong>
<dd>Same as '300deg'. With 'behind', '240deg'.
<dt><strong>left</strong>
<dd>Same as '320deg'. With 'behind', '220deg'.
<dt><strong>center-left</strong>
<dd>Same as '340deg'. With 'behind', '200deg'.
<dt><strong>center</strong>
<dd>Same as '0deg'. With 'behind', '180deg'.
<dt><strong>center-right</strong>
<dd>Same as '20deg'. With 'behind', '160deg'.
<dt><strong>right</strong>
<dd>Same as '40deg'. With 'behind', '140deg'.
<dt><strong>far-right</strong>
<dd>Same as '60deg'. With 'behind', '120deg'.
<dt><strong>right-side</strong>
<dd>Same as '90deg'. With 'behind', '90deg'.
<dt><strong>leftwards</strong>
<dd>Moves the sound
to the left, relative to the current angle.
More precisely, subtracts 20 degrees.
Arithmetic is carried out modulo 360 degrees. Note that
'leftwards' is more accurately described as "turned
counter-clockwise," since it <em>always</em> subtracts 20 degrees,
even if the inherited azimuth is already behind the listener (in which
case the sound actually appears to move to the right).
<dt><strong>rightwards</strong>
<dd>Moves the sound
to the right, relative to the
current angle. More precisely, adds 20 degrees. See 'leftwards'
for arithmetic.
</dl>

<p>This property is most likely to be implemented by mixing the same
signal into different channels at differing volumes.  It might also
use phase shifting, digital delay, and other such techniques to
provide the illusion of a sound stage.  The precise means used to
achieve this effect and the number of speakers used to do so are
user agent-dependent; this property merely identifies the desired end
result.

<div class="example"><P style="display:none">Example(s):</P><P>
<PRE>
H1   { azimuth: 30deg }
TD.a { azimuth: far-right }          /*  60deg */
#12  { azimuth: behind far-right }   /* 120deg */
P.comment { azimuth: behind }        /* 180deg */
</PRE>
</div>

<p>If spatial-azimuth is specified and the output device cannot
produce sounds <em>behind</em> the listening position, user agents
should convert values in the rearwards hemisphere to forwards
hemisphere values.  One method is as follows:</p>

<ul>
    <li>if 90deg &lt; x &lt;= 180deg then x := 180deg - x
    <li>if 180deg &lt; x &lt;= 270deg then x := 540deg - x
</ul>

<div class="propdef">
<dl><dt>
<span class="index-def" title="'elevation'"><a name="propdef-elevation" class="propdef-title"><strong>'elevation'</strong></a></span>
<dd>
<table class="propinfo" cellspacing=0 cellpadding=0>
<tr valign=baseline><td><em>Value:</em>&nbsp;&nbsp;<td><a href="syndata.html#value-def-angle" class="noxref"><span class="value-inst-angle">&lt;angle&gt;</span></a>  | below | level | above | higher | lower | <a href="cascade.html#value-def-inherit" class="noxref"><span class="value-inst-inherit">inherit</span></a>
<tr valign=baseline><td><em>Initial:</em>&nbsp;&nbsp;<td>level
<tr valign=baseline><td><em>Applies to:</em>&nbsp;&nbsp;<td>all elements
<tr valign=baseline><td><em>Inherited:</em>&nbsp;&nbsp;<td>yes
<tr valign=baseline><td><em>Percentages:</em>&nbsp;&nbsp;<td>N/A
<tr valign=baseline><td><em>Media:</em>&nbsp;&nbsp;<td><a href="media.html#aural-media-group" class="noxref">aural</a>
</table>
</dl>
</div>


<P>Values of this property have the following meanings:</p>

<dl>
<dt><span class="index-inst" title="&lt;angle&gt;"><a name="x24" href="syndata.html#value-def-angle" class="noxref"><span class="value-inst-angle"><strong>&lt;angle&gt;</strong></span></a></span>
<dd>Specifies the elevation as an angle, between '-90deg' and '90deg'.
'0deg' means on the forward horizon, which loosely means level with
the listener.  '90deg' means directly overhead and '-90deg' means directly
below.
<dt><strong>below</strong>
<dd>Same as '-90deg'.
<dt><strong>level</strong>
<dd>Same as '0deg'.
<dt><strong>above</strong>
<dd>Same as '90deg'.
<dt><strong>higher</strong>
<dd>Adds 10 degrees to the current elevation.
<dt><strong>lower</strong>
<dd>Subtracts 10 degrees from the current elevation.
</dl>

<P>The precise means used to achieve this effect and the
number of speakers used to do so are undefined.  This property merely
identifies the desired end result.

<div class="example"><P style="display:none">Example(s):</P><P>
<PRE>
H1   { elevation: above }
TR.a { elevation: 60deg }
TR.b { elevation: 30deg }
TR.c { elevation: level }
</pre>
</div>

<h2>19.8 <a name="voice-char-props">Voice characteristic properties</a>: <a href="aural.html#propdef-speech-rate" class="noxref"><span
class="propinst-speech-rate">'speech-rate'</span></a>, <a href="aural.html#propdef-voice-family" class="noxref"><span
class="propinst-voice-family">'voice-family'</span></a>,
<a href="aural.html#propdef-pitch" class="noxref"><span class="propinst-pitch">'pitch'</span></a>,
<a href="aural.html#propdef-pitch-range" class="noxref"><span class="propinst-pitch-range">'pitch-range'</span></a>,
<a href="aural.html#propdef-stress" class="noxref"><span class="propinst-stress">'stress'</span></a>, and
<a href="aural.html#propdef-richness" class="noxref"><span class="propinst-richness">'richness'</span></a></H2>

<div class="propdef">
<dl><dt>
<span class="index-def" title="'speech-rate'"><a name="propdef-speech-rate" class="propdef-title"><strong>'speech-rate'</strong></a></span>
<dd>
<table class="propinfo" cellspacing=0 cellpadding=0>
<tr valign=baseline><td><em>Value:</em>&nbsp;&nbsp;<td><a href="syndata.html#value-def-number" class="noxref"><span class="value-inst-number">&lt;number&gt;</span></a>  | x-slow | slow | medium | fast | x-fast | faster | slower
| <a href="cascade.html#value-def-inherit" class="noxref"><span class="value-inst-inherit">inherit</span></a>
<tr valign=baseline><td><em>Initial:</em>&nbsp;&nbsp;<td>medium
<tr valign=baseline><td><em>Applies to:</em>&nbsp;&nbsp;<td>all elements
<tr valign=baseline><td><em>Inherited:</em>&nbsp;&nbsp;<td>yes
<tr valign=baseline><td><em>Percentages:</em>&nbsp;&nbsp;<td>N/A
<tr valign=baseline><td><em>Media:</em>&nbsp;&nbsp;<td><a href="media.html#aural-media-group" class="noxref">aural</a>
</table>
</dl>
</div>


<P>This property specifies the speaking rate. Note that both absolute
and relative keyword values are allowed (compare with <a href="fonts.html#propdef-font-size" class="noxref"><span
class="propinst-font-size">'font-size'</span></a>). Values have
the following meanings:</p>

<dl>
<dt><span class="index-inst" title="&lt;number&gt;"><a name="x26" href="syndata.html#value-def-number" class="noxref"><span
class="value-inst-number"><strong>&lt;number&gt;</strong></span></a></span>
<dd>Specifies the speaking rate in words per minute, a quantity that varies
somewhat by language but is nevertheless widely supported by speech
synthesizers.
<dt><strong>x-slow</strong>
<dd>Same as 80 words per minute.
<dt><strong>slow</strong>
<dd>Same as 120 words per minute
<dt><strong>medium</strong>
<dd>Same as 180 - 200 words per minute.
<dt><strong>fast</strong>
<dd>Same as 300 words per minute.
<dt><strong>x-fast</strong>
<dd>Same as 500 words per minute.
<dt><strong>faster</strong>
<dd>Adds 40 words per minute to the current speech rate.
<dt><strong>slower</strong>
<dd>Subtracts 40 words per minutes from the current speech rate.
</dl>

<div class="propdef">
<dl><dt>
<span class="index-def" title="'voice-family'"><a name="propdef-voice-family" class="propdef-title"><strong>'voice-family'</strong></a></span>
<dd>
<table class="propinfo" cellspacing=0 cellpadding=0>
<tr valign=baseline><td><em>Value:</em>&nbsp;&nbsp;<td>[[<a href="aural.html#value-def-specific-voice" class="noxref"><span class="value-inst-specific-voice">&lt;specific-voice&gt;</span></a>  | <a href="aural.html#value-def-generic-voice" class="noxref"><span class="value-inst-generic-voice">&lt;generic-voice&gt;</span></a> ],]* [<a href="aural.html#value-def-specific-voice" class="noxref"><span class="value-inst-specific-voice">&lt;specific-voice&gt;</span></a>  |
<a href="aural.html#value-def-generic-voice" class="noxref"><span class="value-inst-generic-voice">&lt;generic-voice&gt;</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>&nbsp;&nbsp;<td>depends on user agent
<tr valign=baseline><td><em>Applies to:</em>&nbsp;&nbsp;<td>all elements
<tr valign=baseline><td><em>Inherited:</em>&nbsp;&nbsp;<td>yes
<tr valign=baseline><td><em>Percentages:</em>&nbsp;&nbsp;<td>N/A
<tr valign=baseline><td><em>Media:</em>&nbsp;&nbsp;<td><a href="media.html#aural-media-group" class="noxref">aural</a>
</table>
</dl>
</div>


<P>The value is a comma-separated, prioritized list of voice family
names (compare with <a href="fonts.html#propdef-font-family" class="noxref"><span
class="propinst-font-family">'font-family'</span></a>). Values have the
following meanings:</P>

<dl>
<dt><span class="index-def" title="&lt;generic-voice&gt;,
definition of"><a
name="value-def-generic-voice"><strong>&lt;generic-voice&gt;</strong></a></span>
<dd>Values are voice families. Possible values
are 'male', 'female', and 'child'.
<dt><span class="index-def" title="&lt;specific-voice&gt;::definition of"><a name="value-def-specific-voice"><strong>&lt;specific-voice&gt;</strong></a></span>
<dd>Values are specific instances (e.g., comedian, trinoids, carlos, lani).