Leonardo Da Vinci, an Italian thinker and artist, was one of the first to discovered that sound moves in waved. He made the discovery around the 1500. Later on, Galileo Galilei discovered more about sound waves. He learned that the frequency of sound waves show how pitched the sound will be. Sound waves move in mediums (liquids, solids, or gases). The sound waves move through the medium by vibrating the molecules in the object. Sound travels faster in solids and slowest in gases. The spacing of the molecules determines how fast sound travels through a gas, liquid, or a solid. Since, the molecules are more spaced in gases and packed in solids sound waves move faster in solids than gases. In air, sound waves are carried by pressure variation from its source to its surroundings. The sound level decreases as it gets farther and farther away from its source. The air absorbs the sound, which causes the sound to weaken. The sound reducing is called attenuation. In air, sound waves are carried by pressure variation from its source to its surroundings. The speed of sound depends on the density and elasticity of the medium, which the sound is moving through. The speed of sounds is different in every object. The closer the molecules are to one another, it takes less time for the sound to move from a molecule to another molecule and the sound moves faster. It is easier for sound to go through solids than liquids or gases because the molecules are packed together. It is harder for sound to pass through gases than liquids because the molecules in gases are farther apart from each other. The speed of sound depends on the density and elasticity of the medium through which it is traveling. A loud noise has a lot more pressure variation than a weak noise, which has a smaller pressure variation. Pressure variation are shown in Pascal, or shorten to Pa, which is defined as N/m² (Newton per square metre).