Sound is a form of energy that is produced by vibrating matter. Where there is no matter there is no sound. Sound waves must have a medium (matter) to travel through. When we talk, sound waves travel in the air. Sound also travels in liquids and solids. How fast speed travels, or the speed of sound, depends on the kind of matter it is moving through. Of the three phases of matter (gas, liquid, and solid), sound waves travel the slowest through gases, faster through liquids, and fastest through solids.
