This controls the loudness of the spoken text. It can be specified with a numeric value which is assumed to be an absolute volume level in the range 0 to 100 and is assumed to be the percentage of the volume range for the platform.
If a percent sign is added, the value inherited from the parent containing element object is multiplied by that percentage for the child element's volume setting.
In addition, these keywords are also supported for defining absolute values:
|See also:||Aural style sheets|