Pitch-range

The CSS   property specifies the degree of variation from the average pitch of the voice being used to render the content. A voice with a small pitch range will sound monotone, while a voice with high pitch range values will sound very animated. The perceived pitch of a human voice is determined by the fundamental frequency and typically has a value of 120Hz for a male voice and 210Hz for a female voice.

Values
HTML example:

OMG!

CSS example:

strong { pitch-range:80; }