I dont think that        theyre all in the same arena means      they speak as one voice.

I tend to agree with Fred.   The emphasis on one voice is wrong.    The emphasis should be on how many different voices can speak differently albeit in the same arena.    I dont think that  

     theyre all in the same arena

means

     they speak as one voice.

If there is A voice of humanity it doesnt speak to us and we dont speak to it.    The part can't know the whole.  A VoH might, however, speak to different species or variouis ET civilizations.    

Our voice is speaking very loudly to many disappearing species, in fact it has a big dialogue with Gaia about the weather.