(a) Sound is produced when the object vibrates. For example, the production of sound from the strings of the guitar is possible because when the strings of the guitar are struck, there is vibrations generation which travels through air molecules and reaches our ear as sound.

(b) Sound from a sound producing body travel through air to reach our ears is explained with the help of a tuning fork. When a tuning fork is struck against a hard surface, there is production of vibrations that travel through air. These waves are longitudinal and move in the same direction as the movement of the sound. This is how the sound reaches to our ears.