Freedom of speech is a fundamental part of American culture. A lot of Americans, or protestors in other countries, would stare down the barrel of a gun to defend it. Unless that gun happens to be this insane SpeechJammer device that renders you incapable of forming coherent sentences.
The SpeechJammer, developed at the National Institute of Advanced Industrial Science and Technology, works because when we speak, we aren't just using our mouths as an "audio out" speaker. We actively listen to what we're saying, and the way we sound dictates how we proceed with our speech. The SpeechJammer screws with that. The "gun" shoots your words back to you, but with a delay of a few hundred milliseconds, which is enough to mess up natural cadence. The effect is called Delayed Auditory Feedback.
The prototypes use a directional microphone and directional speaker, and one had a distance sensor as well, to accurately determine how long the delay needs to be, based on how far away the speaker is.
Strangely, while DAF can cause regular people to stutter, it's also been shown to alleviate those same problems in people with speech impairments.
The main objectives of the SpeechJammer are "turn-taking controller for discussions in a meeting room" and "portable speech-jamming gun". Of the two, the portable speech-jamming seems far more sinister, with its rally-quelling application calling to mind the Arab Spring and the Occupy movement. But think about that first one for a second. Imagine you're in a meeting, and there's a "Shut the hell up, Johnson" button for if you get a little long-winded. It would be the most wonderfully awkward thing ever, right? [Arvix via Tech Review via ExtremeTech]