Sound
Sound is one of those rare physical phenomena that has been correctly explained by the ancient Greeks. They grasped the essential by focusing on the vibrations of musical instrument cords: sound is an undulating phenomenon. Caused by the initial vibratory movement of a body (cord, diaphragm), it moves around the immediate area via the movement of successive units of air in the same way that a wave spreads along the surface of water by means of vertical oscillatory movement. Source: Flammarion science dictionary.