The voice related group properties is combined of these individual properties: speech-rate, voice-family, pitch, pitch-range, stress and richness.

Speech rate

The speech-rate property contains following information:

  1. value: <number>, x-slow, slow, medium, fast, x-fast, faster, slower or inherit;
  2. initial: medium;
  3. applies to: all elements;
  4. inherited: yes;
  5. percentages: N/A;
  6. media: aural;
  7. computed value: number.

This property specifies the speaking rate. The value number defines the speaking rate in words per minute. The pre-defined keywords have these meanings:

  • x-slow = "80" w/min;
  • slow = "120" w/min;
  • medium = "120" ? "200" w/min;
  • fast = "300" w/min;
  • x-fast = "500" w/min;
  • faster = current rate + "40" w/min;
  • slower = current rate - "40" w/min.

Voice family

The voice-family property contains following information:

  1. value: [[<specific-voice>, <generic-voice>],]*, [<specific-voice>, <generic-voice>] or inherit;
  2. initial: depends on user agent;
  3. applies to: all elements;
  4. inherited: yes;
  5. percentages: N/A;
  6. media: aural;
  7. computed value: as specified.

Similar to font-family property this value is the comma separated list of families. The value generic-voice is a voice family with the possibilities of being set to male, female and child. The value specific-voice refers to specific instances and it may be set to different values, i.e. comedian, romeo, etc...

Pitch

The pitch property contains following information:

  1. value: <frequency>, x-low, low, medium, high, x-high or inherit;
  2. initial: medium;
  3. applies to: all elements;
  4. inherited: yes;
  5. percentages: N/A;
  6. media: aural;
  7. computed value: frequency.

This property specifies the average frequency of a speaking voice in Hertz. The value frequency specifies the average pitch of the voice. The values x-low, low, medium, high and x-height, although they look as absolute, they actually will be mapped relative to the frequencies of the current voice family, as different families have different average frequencies.

Pitch range

The pitch-range property contains following information:

  1. value: <number> or inherit;
  2. initial: 50;
  3. applies to: all elements;
  4. inherited: yes;
  5. percentages: N/A;
  6. media: aural;
  7. computed value: as specified.

The property specifies the variation in an average pitch (frequency). The values are given in the range from "0" to "100", with the "0" being a monotone or flat voice and the "100" being highly animated, high pitch voice. The value of "50" is given as an average pitch.

Stress

The stress property contains following information:

  1. value: <number> or inherit;
  2. initial: 50;
  3. applies to: all elements;
  4. inherited: yes;
  5. percentages: N/A;
  6. media: aural;
  7. computed value: as specified.

The property specifies the height of the "local peaks" in the intonation of voice. The property is a companion to the pitch-range property and it is used to exploit higher end audio displays. The values may be given with the range from "0" to "100", with the "50" being the average for a standard English-speaking voice (average pitch is "122kHz"). The value is highly dependent on the language used to speak out the content.

Richness

The richness property contains following information:

  1. value: <number> or inherit;
  2. initial: 50;
  3. applies to: all elements;
  4. inherited: yes;
  5. percentages: N/A;
  6. media: aural;
  7. computed value: as specified.

The richness property specifies the "brightness" of the speaking voice. The values may be given with the range from "0" to "100", with the higher value meaning the more voice will carry, and the lower value will produce a softer, smoother voice.

Example

CSS voice properties example:

 

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