Explain that sound requires a material or medium for propagation and that it travels through different media.
Sound is a form of energy that requires a material or medium for propagation. The medium through which sound travels affects the speed, intensity, and direction of the sound wave. Sound travels through air, water, and solid matter, with air being the most common medium. Sound travels faster in solids than in liquids and faster in liquids than in air. The speed of sound also depends on the temperature and pressure of the medium. As temperature and pressure increase, the speed of sound increases. The direction of the sound wave also depends on the medium—sound waves travel more quickly and in straight lines in solids, while they travel more slowly and in curved paths in liquids and gases.