When an object vibrates, it pushes on molecules of air causing these molecules to bump other molecules passing the motion on. This is how sound travels through air. You can feel these vibrations by placing your fingers against your throat while you talk. You can see these vibrations if you strum any kind of taut string. Sound is a form of energy because it causes matter to move.
Sound travels through liquids.
Sound travels most rapidly through solids. Sounds can be loud or soft. This loudness or softness is its volume. The more energy, the louder the sound. Sound travels through matter by vibration.