voice-rate property CSS Reference

Definition and Usage

This property controls the speaking rate. The default rate for a voice depends on the language and dialect and on the personality of the voice. The default rate for a voice should be such that it is experienced as a normal speaking rate for the voice when reading aloud text. Since voices are processor-specific, the default rate will be as well.

Name: voice-rate
Value: [normal | x-slow | slow | medium | fast | x-fast] || <percentage>
Initial: normal
Applies to: all elements
Inherited: yes
Percentages: refer to default value
Media: speech
Computed value: a keyword value, and optionally also a percentage relative to the keyword (if not 100%)


voice-rate: [normal | x-slow | slow | medium | fast | x-fast] || <percentage> ;



Represents the default rate produced by the speech synthesizer for the currently active voice. This is processor-specific and depends on the language, dialect and on the "personality" of the voice.

x-slow, slow, medium, fast and x-fast

A sequence of monotonically non-decreasing speaking rates that are implementation and voice -specific. For example, typical values for the English language are (in words per minute) x-slow = 80, slow = 120, medium = between 180 and 200, fast = 500.


Only non-negative percentage values are allowed. This represents a change relative to the given keyword value (see enumeration above), or to the default value for the root element, or otherwise to the inherited speaking rate (which may itself be a combination of a keyword value and of a percentage, in which case percentages are combined multiplicatively). For example, 50% means that the speaking rate gets multiplied by 0.5 (half the value). Percentages above 100% result in faster speaking rates (relative to the base keyword), whereas percentages below 100% result in slower speaking rates.


body { voice-rate: inherit; } /* the initial value is 'normal'
                               (the actual speaking rate value
                               depends on the active voice) */
e1 { voice-rate: +50%; } /* the computed value is
                          ['normal' and 50%], which will resolve
                          to the rate corresponding to 'normal'
                          multiplied by 0.5 (half the speaking rate) */
e2 { voice-rate: fast 120%; } /* the computed value is
                          ['fast' and 120%], which will resolve
                          to the rate corresponding to 'fast'
                          multiplied by 1.2 */
e3 { voice-rate: normal; /* "resets" the speaking rate to the intrinsic voice value,
                            the computed value is 'normal' (see comment below for actual value) */
     voice-family: "another-voice"; } /* because the voice is different,
                                      the calculated speaking rate may vary
                                      compared to "body" (even though the computed
                                      'voice-rate' value is the same) */

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