To cut the interception of the conversions at the origin it is enough to act on the microphone, from years the market have listed different devices, like white noise, high audio noise room isolation with a headphone and microphone erase noise capable to use with conversationalists like the DRUID System:
Now with the intermodulation of microphones using ultrasound system that make any type of microphone unusable! Vendors are created different systems, small, bigger, but this system have a lot of limits:
- Ultrasound are super directive, if the mic are not in front at the emitters, it will be able to recording;
- Ultrasound can not penetrate tissue, so if the mic are in the pocket or the phone are in the jacket pocket, this maybe will record all;
- Not all microphones are ultrasound sensible, for example the 20$ cheap, Amazon USB Key recorder, will be able to recorder all audio;
- The price of every system is very high, but this systems will not work proprerly for the different problems, power, type of microphone, directivity of beam, so you need to put a lot of systems to cover all the dark corner and raise the power to penetrate and reach recorders under tissue or conceleated behind furniture panel or something like that;
For the wall and windows, exists a lot of items, this work with vibrations, and directional noise, so external microphones not are able to record inside room conversations, acting like acustic barriers, creates a perimeter of noise that defeats acoustic leakage eavesdropping devices including wired microphones inside walls, contact microphones, audio transmitters located in AC outlets, and laser/microwave reflections from windows:
Also there’s a system composed of adhesive film, that will shields glass from laser microphone attacks, causing it to bounce back irregularly.