Looking for half duplex simulation algorithm

Hi Everybody,

I'm working in an application which enables clients to transmit audio to each other in full duplex. We want to make the system half duplex - what we are going to do is compare the incoming Audio wave to the outgoing, and if the outgoing wave is stronger - we are going to broadcast. If not, (Outgoing < Incoming) then we are going to block it. Is Anyone familiar with algorithm how do such comparison ( what to convert - average, pick ?)

Thanks, Ron