Sound in Space
Spacial characteristics of sound make it easier to tell various voices apart, by placing them in different locations in space. There are two CSS properties that define where the voice is spatially: azimuth and elevation. Azimuth has the following values:
This is the exact degree number for where the voice should be coming from, for example 30deg or 359deg
This keyword places the sound as coming from behind rather than the front
This keyword subtracts 20 degrees from the current angle, making the sound come from the left
This keyword adds 20 degrees to the current angle, making the sound come from the right
The properties of voice characteristics specify what the voices will sound like. This includes details such as their speed of speech, pitch, and range. The properties are:
This indicates the speed of speech, generally in words per minute. The options are:
A specific number of words per minute.
80 words per minute (WPM)
Adds 40 words per minute to the current speech
Subtracts 40 words per minute from the current speech
Similar to the "font-family" property, this is a comma separated list of generic and specific voices. Generic voices are like “male,” “female,” and “child.”
This property defines the specific pitch or frequency of the voice. Possible values are:
A specific value in hertz (Hz)
These don't have specific values as they depend upon what voice-family is used. For example, an x-high male voice might have a lower pitch than a medium or low female voice.
This indicates the variation in average pitch for the voice. The default value is 50, but you can change it to any number between 1 and 100.
This indicates the amount of stress or "local peaks" should be applied to the voice. The default value is 50, but you can change it to any number between 1 and 100.
This determines the richness or brightness of the voice. A rich voice will "carry" through a large room while a smooth voice will not. The default value is 50, but you can change it to any number between 1 and 100.
These properties define how more complex parts of speech like punctuation and numerals are spoken within the element. There are two properties:
This defines how punctuation is spoken
Punctuation is to be spoken literally within the text.
Punctuation is not to be spoken, but to be rendered as natural speech with pauses.
This defines how numbers are spoken
Each separate number is spoken individually. ie. 163 is said "one" "six" "three"
Numbers are spoken as full numbers. ie. 163 is said "one hundred sixty-three"