Sound is a Mechanical Wave in that it needs a medium to travel through. It is also Longitudinal which means it must compress and decompress the molecules in the same direction as the wave is traveling. That being said, sound can pass through all materials but how much it is absorbed depends upon the thickness and type of material. To give a good example, consider castle walls that are 4 feet thick and made of stone. If someone was playing loud music in the next room you would be hard pressed to hear anything. However if the walls were just 2 inches thick you would be able to hear the music (especially the bass). So bottom line, the only thing cannot pass through would be a vacuum as there are no molecules to set in vibration. Everything else will transmit sound.
