If you want to make sure that the sound in the room doesn't flow through prying ears, this is also a way to speak with a small voice. The point is, you need to make it difficult to read, so that the voice cannot be picked up by the eavesdropper's little microphone.
The concrete microphone makes it possible to hear the sound of the room along the wall without using radio waves. Listen-in interceptors can also be used to combat concrete microphones. There is also a model with a specialized function in concrete microphone measurements to transmit vibrations to the wall and disturb it.
The situation in which a conference is being organized for the first time in which such a wiretap jammer will be useful. Because a portable wifi jammer is portable, it is an effective way to defend against wiretapping if you don't have time to research and find a wiretap device.