Abstract: An eavesdropping-proof room comprises boundary components that are substantially transparent, at least from one surface thereof, whereby any device implanted therein is immediately visible. Sound dampening devices for aerating closed rooms are also provided, which comprise, optionally in combination with a fan or other device for withdrawing or introducing air, a casing, a number of partitions dividing said casing into various compartments and a number of channels connecting said compartments in such a way as to determine a zigzag path of the air flowing through the device and the withdrawal of a fraction of the air from each compartment, which results in a dampening of sounds carried by such air.