Spoken language is unique to the homo species. Putting the sounds together into a clear structure that everyone could understand lead to complex language. This enabled individuals to share ideas and concepts, like never before leading to an explosion of human culture. 

From a physiological perspective it was the newly evolved position of the hyoid bone in the throat that allowed humans to form words. But much earlier than the advent of speech the voice permitted another level of communication.  

The voice reveals our emotions. The sounds of anguish and despair or of triumph and joy are universally understood and compelling. The tone of voice tells us more than the words that are spoken; it is primal, animal – a key component of the Social Nervous System.