voice cancelling headset

Laud crowd open office can be more pleasant if we can reduce the level of voice noise. Except partitions the only option is voice cancelling. There are some headsets which create better experience with such an active system - microphone records the voice and the small speaker behind sends negative frequencies to eliminate external sound.  Acoustics engineering companies create sophisticated active 3d acoustics to reduce or enrich the sound vibrations in music halls.
The idea is to give phone operators some device with backward side active headset - where the voice will be cancelling outside the small perimeter:

   Besides there will be multiple microphones, which should mean better sound quality (stereo...).