The following content is excerpted from the end of Chapter 6, Aural Media Styles, and is provided to give potential readers an idea of how information is presented in this book. While some attempt was made to style the content in a manner similar to that used in the book, it will not be exactly the same in all browsers, nor can it be assumed to be an exact mirror of the printed page.
stress
stress specifies the amount of inflection which is used to speak stress markers in a language.
Summary
Values
<number> | inherit
Initial Value
50
Percentages
n/a
Inherited
yes
Applies to
all elements
Media Groups
aural
Values
<number>
Defines the range of stress inflection. The actual meaning of this value will depend on the language being spoken, as different human languages permit different ranges of stress inflection. The exact mechanism is not given in the specification. In general, higher values will lead to greater inflection on stress markers, while lower values will lessen the stress inflection.
Notes
According to the specification, stress refers to "the height of 'local peaks' in the intonation contour of a voice." As an example, the English language uses stress markers to highlight various parts of a sentence using primary, secondary, and tertiary stress. stress combines with pitch-range to produce the nuances of a given language.
Examples
strong {stress: 80;}
div.aside {stress: 40;}
Related Properties
pitch-range, voice-family
voice-family
voice-family is used to define the specific voice, and optionally a generic voice type, which is to be used in the speaking of content.
Summary
Values
[[<specific-voice> | <generic-voice> ],]* [<specific-voice> | <generic-voice> ] | inherit
Initial Value
UA dependent
Percentages
n/a
Inherited
yes
Applies to
all elements
Media Groups
aural
Values
<specific-voice>
Any specific voice name may be declared for the voice, although those voice names with whitespace or other special characters in their names should be quoted.
<generic-voice>
The permitted generic voice family values are male, female, and child.
Notes
In effect, voice-family is the equivalent of font-family for aural media.
Examples
body {voice-family: JoeBob, Cuthbert, male;}
*.fem {voice-family: Julie, "Ma Bell", Aenea, female;}
Related Properties
pitch, pitch-range, stress, richness
volume
volume describes the "loudness" of a sound.
Summary
Values
<number> | <percentage> | silent | x-soft | soft | medium | loud | x-loud | inherit
Initial Value
medium
Percentages
refer to inherited value
Inherited
yes
Applies to
all elements
Media Groups
aural
Values
<number>
Any number in the range 0 - 100. The actual decibel levels which correspond to the volume number values 0 and 100 are meant to be set by the user agent. For this reason, the specification defines the number 0 as the minimum audible level, and 100 as the maximum comfortable level. This is due to the fact that different environments require different decibel ranges for comfortable hearing. For example, the setting for 0 should be different when driving in a car than the setting in a home office; similarly, the setting for 100 will be different in a library than in a teenager's bedroom. This approach allows users to set the volume range appropriate for their diverse environments while still making use of the same author stylesheet. This also means that the value 0 will produce some sound, at whatever decibel level is set to be the minimum audible level for the current user environment.
<percentage>
Percentage values are calculated relative to the inherited value of volume, and then clipped to the range 0 - 100 if necessary.
silent
No sound should be produced. Thus, silent and 0 are not equivalent, as 0 could produce a 30-decibel sound or a 5-decibel sound, depending on the user agent's settings. Like the mute button on a television, silent will always result in a lack of any sound, regardless of the user agent settings. However, the time it would normally have taken to play the sound (or read the text) will be filled with silence. In other words, the user agent still attempts to play a sound or read text, but produces no actual sound. This is somewhat equivalent to the visual style visibility: hidden, which causes elements to be invisible but take up the space which would be required to display them.
x-soft
Equivalent to the numeric value 0.
soft
Equivalent to the numeric value 25.
medium
Equivalent to the numeric value 50.
loud
Equivalent to the numeric value 75.
x-loud
Equivalent to the numeric value 100.
Notes
In more precise terms, volume, to quote the specification, sets "the median volume of the waveform... In other words, a highly inflected voice at a volume of 50 might peak well above that." Thus, volume does not enforce exactly the same volume level for every sound produced, but instead defines the midpoint of the sounds which are produced. In addition, the property volume is intended to adjust the dynamic range of a sound, since it cannot be expected to override physical controls like volume knobs.
Examples
div.sotto {volume: 33;}
h1 {volume: loud;}
*.quiet {volume: 0;}
*.mute {volume: silent;}
Related Properties
speak