HTML and CSS Reference
In-Depth Information
envision a time in the near future when you may be able to take advant-
age of some or all of these properties.
8.4.12.1. The volume property
The most basic aural property is
volume
. It accepts numeric length or
percentage values along with a few keywords corresponding to preset
volume levels.
Numeric values range from 0 to 100, with 0 corresponding to the min-
imum audible level and 100 being the maximum comfortable level. Note
that 0 is not the same as silent, as the minimum audible level in an en-
vironment with loud background noise (like a factory floor) may be quite
high.
Percentage values compute an element's volume as a percentage of the
containing element's volume. Computed values less than 0 are set to
0; values greater than 100 are set to 100. Thus, to make an element
twice as loud as its parent element, set the
volume
property to
200%
. If
the volume of the parent element is 75, the child element's volume gets
set to the limit of 100.
You also may specify a keyword value for the
volume
property. Here,
silent
actually turns the sound off. The
x-soft
value corresponds to a
value of
0
;
soft
is the same as the numeric volume of 25;
medium
is 50,
loud
is 75, and
x-loud
corresponds to 100.
8.4.12.2. Speaking properties
Three properties control whether and how text is converted to speech.
The first is
speak
, which turns speech on and off. By default, the value
of
speak
is
normal
, meaning that text is converted to speech using stand-
ard, locale-specific rules for pronunciation, grammar, and inflection. If
you set
speak
to
none
, speech is turned off. You might use this feature to
suppress speaking of secondary content or content that does not readily
translate to audio, such as a table.
