How to jam annoying talkers
March 5, 2012 by Amara D. Angelica
Attention, telephone babblers, library whisperers, and hecklers: Japanese researchers at the National Institute of Advanced Industrial Science and Technology want you to shut the bleep up.
They’ve developed the “Speech-jammer” gun, which will reduce you to incoherent stuttering from up to 90 feet away.
It works by recording your words and then sending them back with a delay of a few hundred milliseconds (it’s more effective when the time delay varies). The “delayed auditory feedback” (DAF) effect is similar to what you experience when echo suppression fails on Skype voice chat.
How to make it
As described in the arXiv reference cited below, the device basically includes a laser pointer, directional microphone, distance sensor, microcomputer for delay, and parametric (directional) speaker. The parametric speaker modulates the voice audio onto an ultrasonic beam, which perturbs the air in a narrow beam, demodulating the audio to generate audible sound to anyone within that beam.
The speaker uses a “parametric array” — the same principle as the Audio Spotlight and the HyperSonic Sound System. (That could be how the targeted audio advertising in Minority Report (video below) would work.) Construction information is here.
How to block it
Wear noise cancellation earpieces; trace the path of the laser beam (an IR laser would require a night-vision detector); or use an array of microphones in a circle with a comparator circuit to detect the direction of the sound beam.
Ref.: Kazutaka Kurihara, Koji Tsukada, SpeechJammer: A System Utilizing Artificial Speech Disturbance with Delayed Auditory Feedback, arXiv.