Distributed acoustic conversation shielding is the subject of a new patent by MIT Media Lab researchers. The device is designed to protect the privacy of spontaneous workplace conversations with sound from distributed loudspeakers. The units could be disguised as power strips.
This usage scenario is taken from the earlier paper Distributed Acoustic Conversation Shielding:
An Application of a Smart Transducer Network by Yasuhiro Ono*, Joshua Lifton, Mark Feldmeier, Joseph A. Paradiso.
An office worker happened to meet one of his colleagues, a team member of a project, in the open space of their office area, and they started to chat about their project. He noticed that the content of the conversation was getting rather confidential to people outside their team. He pushes a button on his mobile device to trigger the acoustic conversation shielding application, at which point, various speakers surrounding them start to emit a masking sound to prevent others from overhearing the conversation. When the conversation is over, he pushes the button again to stop the masking.
Here's a prototype version of a conversation shielding wearable controller.
They actually tested this idea with a network of 12 units, about two meters apart, with some success. The masking sounds decreased the signal-to-noise ratio by 5-10 dB at each location.
Science fiction readers (and television watchers) find this idea familiar. Most of us recall the cone of silence made famous in the Sixties television show Get Smart. Take a look at this commercial which shows the cone of silence in use.
(Cone of silence in Get Smart)
Perhaps more specifically, Frank Herbert used the term and the basic idea and the term cone of silence in his 1958 short story Cease Fire.
SF readers also recall the Fenton silencer from Arthur C. Clarke's 1957 story Silence Please.
It consisted of a microphone, a special amplifier and a pair of loud speakers. Any sound that happened to be about was picked up by the mike, amplified and inverted so it was exactly out of phase with the original noise. Then it was pumped out of the speakers, the original wave and the new one cancelled out, and the net result was silence.
(Read more about Clarke's Fenton silencer)
A year earlier, Robert Heinlein wrote about a hush corner in his 1956 novel Double Star.
Sometimes such facilities in public places like hotels are not all that they might be; the sound waves fail to cancel out completely. But the Eisenhower is a luxury house and in this case, at least, the equipment worked perfectly; I could see their lips move but I could hear no sound.
As far as I know, the earliest use of the cone of silence term and idea occurred in a 1955 episode of Science Fiction Theatre entitled "Barrier of Silence."