HTML and CSS Reference
In-Depth Information
In lieu of a URL representing the background sound, you can use the
value
none
. This lets you silence all background sounds, such as one or
more playing from parent elements, while the current element is being
spoken.
8.4.12.7. Spatial positioning
While a rendered document exists on a two-dimensional page, spoken
content can be placed anywhere in the three-dimensional space sur-
rounding the listener. The CSS2 standard defines the
azimuth
and
elev-
ation
properties so that you can place spoken content from elements in
different places around the listener.
azimuth
relates to where and
eleva-
tion
tells how far above or below the sound appears to the listener.
The
azimuth
property accepts either an angle value or keywords indic-
ating a position around the listener. The position directly in front of the
listener is defined to be 0 degrees. The listener's right is at 90 degrees,
and directly behind is 180 degrees. The listener's left is at 270 degrees
or, equivalently, -90 degrees.
Position keywords include a base position, possibly modified by the
be-
hind
keyword. These keywords correspond to the angular positions lis-
ted in
Table 8-2
.
Table 8-2. Angular equivalents for azimuth keywords
Angular posi-
tion
Angular position when used with be-
hind
Keyword
left-side
270
270
far-left
300
240
