Silence is golden, so there are plenty of times when it'd be awfully convenient to mute those around us, and a couple of Japanese researchers have created a gadget that can do just that. Called the SpeechJammer, it's able to "disturb remote people's speech without any physical discomfort" by recording and replaying what you say a fraction of a second after you say it. Why would that shut up the chatty Cathy next to you? Delayed auditory feedback (DAF) is based on an established psychological principle that it's
