How do sound waves travel through a material?

A sound wave is a disturbance. When it travels through air, it bounces the air molecules around and they vibrate. They then hit other molecules and cause a chain reaction. In a different material, such as metal, sound actually travels faster. this is because the molecules are much more tightly packed (water is not dense because the molecules just roll over each other, and air is even less dense, with its molecules simply floating). This means the disturbance (sound wave) can hit more molecules and travel faster. Imagine having a big line of soccer balls, each 1 foot apart. When you kick the first, it takes a while for it to hit the second, then longer to hit the third, and so on. But if the balls were so close they almost touched, as soon as you kicked one, the last ball on the end would be moving almost instantly. This is how sound waves travel through metal and air.

Greco