Idea: Volume-leveled Conference Call Service

Ever been on a conference call where one participant's a mumbler and another one's a shouter?  You're pressing your phone to your ear to hear what the first guy says, and then the other guy gets on and blasts your ear-drum out?

Well how about a simple (?) add-on to a conference call service that would automatically level the volume of the participants?  Phase 1 would work just like the Audio set up on your computer - you'd repeat a short sentence; Phase 2 would be to level the audio in real-time.

Come on, somebody build this, or point me to someone that already offers this.

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