[学习笔记] CSS2 听觉参考

听觉样式表

听觉样式表可把语音合成与音响效果相组合，使用户可以听到信息，而无需进行阅读。

听觉呈现可用于：

• 视觉能力低弱的人士
• 帮助用户学习阅读
• 帮助有阅读障碍的用户
• 家庭娱乐
• 在汽车中使用

听觉呈现通常会把文档转化为纯文本，然后传给屏幕阅读器（可读出屏幕上所有字符的一种程序）。

听觉样式表的一个例子：

h1, h2, h3, h4 { voice-family: male; richness: 80; cue-before: url("beep.au") } 

上面的例子可以让语音合成器演奏一段声音，然后用男性的声音读出标题。

CSS2 听觉参考

W3C : "W3C" 列的数字显示出属性由哪个 CSS 标准定义（CSS1 还是 CSS2）。

属性	描述	值	W3C
azimuth	Sets where the sound/voices should come from (horizontally)	angle left-side far-left left center-left center center-right right far-right right-side behind leftwards rightwards	2
cue	A shorthand property for setting the cue-before and cue-after properties in one declaration	cue-before cue-after	2
cue-after	Specifies a sound to be played after speaking an element's content to delimit it from other	none url	2
cue-before	Specifies a sound to be played before speaking an element's content to delimit it from other	none url	2
elevation	Sets where the sound/voices should come from (vertically)	angle below level above higher lower	2
pause	A shorthand property for setting the pause-before and pause-after properties in one declaration	pause-before pause-after	2
pause-after	Specifies a pause after speaking an element's content	time %	2
pause-before	Specifies a pause before speaking an element's content	time %	2
pitch	Specifies the speaking voice	frequency x-low low medium high x-high	2
pitch-range	Specifies the variation in the speaking voice. (Monotone voice or animated voice?)	number	2
play-during	Specifies a sound to be played while speaking an element's content	auto none url mix repeat	2
richness	Specifies the richness in the speaking voice. (Rich voice or thin voice?)	number	2
speak	Specifies whether content will render aurally	normal none spell-out	2
speak-header	Specifies how to handle table headers. Should the headers be spoken before every cell, or only before a cell with a different header than the previous cell	always once	2
speak-numeral	Specifies how to speak numbers	digits continuous	2
speak-punctuation	Specifies how to speak punctuation characters	none code	2
speech-rate	Specifies the speed of the speaking	number x-slow slow medium fast x-fast faster slower	2
stress	Specifies the "stress" in the speaking voice	number	2
voice-family	A prioritized list of voice family names that contain specific voices	specific-voice generic-voice	2
volume	Specifies the volume of the speaking	number % silent x-soft soft medium loud x-loud	2