Anti Surveillance System 
The Anti Survailance System, is used to foil electronic listening
devices, or "bugs". It will discourage or foil ambient room bugging
during sensitive or classified telephone conversations or face-to-face
conversations, and during intelligence bearing sound transmissions. It
masks an acoustic target signal, e.g., a voice or voices, conversation
or intelligence-bearing communication, and/or any acoustic sound which
may contain intelligence. A specially constructed masking signal is
acoustically generated / reproduced for the duration of the acoustic
target signal, to render the acoustic target signal unintelligible,
and extremely difficult, if not impossible, to isolate or listen in
on.

...for more info visit our website at:
http://www.alternative-technologies.org/security.html