Sound is produced due to the to and fro or back and forth motion of an object known as vibration. When a tightly stretched band is plucked, it produces sound. When it stops vibrating, it does not produce sound.
Sound waves enter the ears and travel down a canal at the end of which is a thin, tightly stretched membrane called eardrum. As the sound wave strikes the eardrum, it vibrates and the vibrations reach the inner ear which sends signals to the brain. The brain interprets the signals and we hear the sound.