Professor Lee Sam-hyeon’s research team has developed a new technology that enables sound to be transmitted through walls. Their research was recently published in Physical Review Letters (IF 7.37), a prestigious journal of the American Physical Association. Because solid walls reflect most sounds, transmitting sound through such walls has been considered nearly impossible. While there are microscopic holes in such walls, the sound that is transmitted through the wall is usually negligible. For sound to pass through these holes, which are smaller than the size of a sound wave, the air in the holes must be made to vibrate rapidly. Professor Lee’s team has found a way for sound to be effectively transmitted through such holes. This was accomplished by covering the small holes with a thin tensioned elastic film. To increase the amount of transmission, more energy has to permeate the hole; and to do this the air must move much faster than the air on the other side of the wall. For the air to move rapidly, the efficiency mass needs to be brought down to almost zero. This was accomplished through the vibration of the elastic film. When the film produced resonance, it vibrated like a little speaker and created waves that were transmitted through the wall. The results of this study are anticipated to be applied to research on supersensitive sound sensors as well as other devices such as telescopes, noise filters, new types of windows, and sound concentration equipment.