1) loudness = (amplitude)2
loudness of the sound becomes 9 times. i.e it increases with greater amplitude.
2) If surface area is of the vibrating body is increased , loudness of sound is also increased.
3)the distance between the source and the listener is doubled :
loudness of sound is inversely proportional to the square of the distance.
Lesser the distance between the source and the listener, greater is the loudness of the sound heard by the listener and vice -versa.
4)if density of medium decreases, lesser is the loudness of the sound. The loudness of the sound is directly proportional to the density of the medium through which it propagates.