The W3C CSS working group has updated the working draft of
CSS3
Speech Module.
This spec defines CSS properties used
when documents are read out loud. These include
voice-volume, voice-balance,
speak, pause-before,
pause-after, pause,
cue-before, cue-after,
cue, mark-before, mark-after, mark, voice-rate,
voice-family, voice-pitch,
voice-pitch-range, voice-stress,
voice-duration, phonemes,
@phonetic-alphabet. This draft
aligns "the definitions with the latest version of SSML as it reached W3C Recommendation status. This effects voice-volume, voice-rate, voice-pitch, voice-pitch-range, and voice-stress, where the enumerated logical values are now defined as monotonically non-decreasing sequences to match SSML. Named relative values such as louder and softer have been dropped since they are not supported by SSML and can't be related through percentage changes to the enumeration of logical values."