What is loudness of sound? What factors does it depend on?

(N/A) Loudness is the measure of the degree of sensation of sound produced in the ear. It is a physiological response of the ear to the intensity of sound.
Loudness depends primarily on the $amplitude$ of the vibration producing the sound. The greater the $amplitude$ of vibration,the louder the sound produced.
Additionally,loudness depends on the force with which an object is made to vibrate and the surface area of the vibrating object.