Sound waves are produced vibrating object. Whether its be the sounds of a person's voice, the sound of a piano, sound of a trombone or the sound of a physics book slamming to the floor, the source of a sound is always vibrating object.
A tuning fork serves as a illustration of how a vibrating object can produce sound.
The fork consists of a handle and two tines. When the tuning fork is hit with a rubber hammer, the tines begin to vibrate. The back and forth vibration of the tines produce disturbances of surrounding air molecules.