Japanese researchers have created a device to perpetuate the definition of "silence is golden," by remotely cutting off human speech without any physical discomfort or intervention. So with what looks like a handheld speed camera, you can literally mute a person: a piece of technology many of us here wish we can acquire.
So how exactly does the SpeechJammer do this? It's all based around the established psychological principle called Delayed Auditory Feedback (DAF), as explained in the paper written by the researchers, where if our spoken words are repeated to us within a fraction of a second of them being said, it has a direct impact upon our cognitive process and makes it nigh-on impossible for anyone to speak.
With this in mind, the prototype of a combined microphone and speaker encased in acrylic makes for a device that can easily 'jam' speech. Plus the directional technology of the mic and speaker means you can target a specific individual. The built-in motherboard processes the delay and playback, enabling you to just point and shut someone up.
Potential uses in the paper are listed as public libraries and unruly discussions; but beyond this, unfortunately, there isn't any mention of taking the gadget to market. For the 'death by powerpoint' situations in the office, or that particular friend who dominates a conversation, we wouldn't mind having one around.
Source: arXIv.org (PDF)