How to protect the conversation in the house from evasdropping using microphone listening through walls?
My house is townhouse, walls are made of concrete, 6 inches thick. The next house beside my house shares the same walls with my house. I think he put the microphone through walls because even I just whispered he can hear it and know every conversation in my house. Please instruct me the countermeasure or cheap DIY device that work effectively to protect this situation.