The idea is based on the fact that to speak properly, we humans need to hear what we’re saying so that we can constantly adjust how we go about it, scientists call it delayed auditory feedback. It’s partly why singers are able to sing better when they wear headphones that allow them to hear their own voice as they sing with music, or use feedback monitors when onstage. Trouble comes though when there is a slight delay between the time the words are spoken and the time they are heard. If that happens, people tend to get discombobulated and stop speaking, and that’s the whole idea behind the SpeechJammer. It’s basically just a gun that causes someone speaking to hear their own words delayed by 0.2 seconds.