Have you ever had a quiet and peaceful moment ruined by an inconsiderate person making an obnoxiously disruptive but probably pointless phone call? You might not have guessed it, but repeating everything they say right after they say it has a research proven effect on shutting them up. You can thank all of the toddlers for that one.
Taking advantage of this phenomenon known as Delayed Auditory Feedback, Japanese researchers Kazutaka Kurihara and Koji Tsukada created a device that replays your speech so quickly that it renders you speechless. Although it will may not be as effective on some as it is on others, research has shown that DAF can produce varying levels of mental stress, making speechlessness a definite possibility.
Called the "SpeechJammer", this gun-shaped device features a directional microphone and speaker, allowing the device to disrupt the speech of a specific target that is within range. The idea behind the device is that the microphone records what you say and the speaker replays it within milliseconds, causing delayed auditory feedback and a possible impact on cognitive processes.
We have our own doubts about the efficacy of the device though. It may be a pretty neat idea in theory, but pulling off the use of such a device without any kind of interference, feedback or range issues may be challenging. Not to mention the fact that it has to be pointed directly at the target's face. Regardless, if the researchers do somehow produce a commercial-ready version, all of the librarians of the world will be pretty happy.