How does loudness of sound is affected by amplitude?

Explanation

Loudness of sound is proportional to the square of amplitude of the vibrations producing the sound. If the amplitude becomes twice, the loudness increases by a factor of four. The unit of loudness is decibel (dB). The sound 80 dB becomes physically painful. The loudness of sound depends on the amplitude. When the amplitude of vibration is large the sound produced is loud, when the amplitude is small the sound produced is feeble.