The primary responsibilities of human resources are: 1  C - Compensation. 2  H - Human resource development. 3  E - Employee and labor relations. 4  S - Safety and health. 5  S - Staff.
A new technique uses sound waves to levitate objects and move them in mid-air. Credit: Dimos Poulikakos View full size image. View full size image. Hold on to your wand, Harry Potter: Science has outdone even your best Leviosa! levitation spell.
Re your last comment if we said some of the sound waves passes through the wall: you need to remember that a sound wave is not a thing. It's just the movement of something else. In air a sound wave is a movement of the atoms in air, and in a wall a sound wave is the movement of the atoms in the wall.