Ultimately, technology is limited. What you need is a culture of "library voices". To wit: "Don't raise your voice unless you absolutely have to. Better, don't use your voice, period, if you can just do a chat session with the person. If you must use your voice -- just keep the volume down, and and the duration minimal. If you must have a full-volume conversation for any length of time -- get a room."

Basically, people in office environments get used to "yapping" for a whole lot of reasons not related to any actual need to exchange information (to vent and shoot the shit, basically) and to do so in rollicking, loud "party" voices without any regard to the downsides. Meanwhile, all it takes is a bit of introspection to realize that about 80% of this noise is just that. And a little bit of discipline to institute a culture of (relative) quiet and solitude -- even in an open plan office.

What, you say -- no time for introspection? No interest in discipline? No way to even bring up the idea of "library voices" in your culture?

Then your problems are much bigger than can what be helped by any advanced technology.