say we don't want to be overheard? go on, say it...
ok, so we could go to a sound proof room. or we could get everyone around us to wear noise cancelling headphones (good luck with that). or we could design a noise cancelling drone.
we'd put our phones on the table in front of us, and run an app that transmits the sound from all the phones' mikes to the drone, which then computes the audio signal that is being propagated from our table, and (using a phase array speaker system) transmits the reverse phase of that.
it has to e on the drone because a) that's hip, cool, fashionable and fun and b) you can't run it on the phone or the people you are talking to across the table wont hear you either.
you heard it here first. or maybe you didn't.