It never fails to amaze me how talented people choose to spend their talent. Freedom of speech? Not with this gun. The Japanese have developed a gun that shoots sound waves and silences anyone that would dare to speak. It works by delayed auditory feedback (see http://news.yahoo.com/blogs/technology-blogblog/weird-gun-future-attacks-words-not-people-1.) The gun, which looks like a large laser gun used by police for speeders, picks up sound and plays it back .02 seconds later. The brain is confused and makes it almost impossible to speak.
Normally the human brain hears the voice in sync during regular speech and can process what it hears. But when it hears an echo, it shuts down the part of the brain designated for speech rendering the recipient of the Silence Gun unable to speak.
The future of this technology is chilling. Will it be a larger "gun" mounted on a building that will "allow" citizens to remain silent during speeches? What are the short and long term affects on the brain? This technology bears watching.