Human sounds are made by using the vocal chords.
Something must move for sound to be made.
Sound is made by something vibrating.
For example, when a bell rings, the sound vibrations vibrate the air, which, when it reaches our ears, make the tiny bones in our middle ear vibrate at the same frequency.
This vibrating message is picked up by the auditory nerve connected to the inner ear, then transmitted to the brain where it is interpreted by the auditory centers.
Altering the vibration changes the sound (it may make it louder or softer, or it may make a change intone or pitch).
Sound travels away from the source of the sound in all directions and can travel through a gas, liquid or solid.
The further the sound vibrations get from their source, the weaker they become