http://news.poseidon-us.com/TGCKdp
Researchers have created a headphone prototype that allows listeners to hear people speaking within a bubble with a programmable radius of 3 to 6 feet. Voices and sounds outside the bubble are quieted an average of 49 decibels, even if they’re louder than those in the bubble.
http://news.poseidon-us.com/TGCKdp
http://news.poseidon-us.com/TGCKdp