Japanese researchers have invented a machine that can shut someone up at will, the Daily Mail reported.

Kazutaka Kurihara and Koji Tsukada have built a gun they call the "Speech Jammer", which could be ideal for an unruly classroom or noisy library.

It is accurate when fired from up to 30 meters away. When it is shot at a speaker, it keeps them quiet almost instantly using a technique called "Delayed Auditory Feedback".

Rather than causing the person pain, it will stress them into shutting up by recreating an uncomfortable feeling that most people will have experienced when they hear their own voice echo back to them during a phone call or on Skype.