CSS stress property

This property specifies the height of "local peaks" in the intonation contour of a voice. English is a stressed language, and different parts of a sentence are assigned primary, secondary, or tertiary stress. 

The possible values are −

• number − A value between '0' and '100'. The meaning of values depends on the language being spoken. For example, a level of '50' for a standard, English-speaking male voice (average pitch = 122Hz), speaking with normal intonation and emphasis would have a different meaning than '50' for an Italian voice.