Distinguish between loudness and intensity of sound.

Question

Distinguish between loudness and intensity of sound.

Answer 1

Loudness is related to the amplitude of sound waves (or pressure amplitude/ displacement relative to atmospheric pressure, typically), whereas intensity is the rate at which power (rate of energy transfer, or work per unit time) is transferred across a given area (Power/Area, or rate of energy transfer per unit area; units of watts/m²). 

Check out this hyperphysics link for more details.
http://hyperphysics.phy-astr.gsu.edu/hbase/sound/loud.html#c1

Answer 2

In other words, intensity is how strong your sound meter reads that a sound is, loudness is how strong your ear perceives it is. They're quite different scales, because your nervous system tries to take in much more range for signals than a simple, linear detector would be able to, using mechanisms like hinged bone assemblies in the ear, changeable pupil diameters and light adaptation in the eye, adjustable taste tolerance for capsaicin (for example!), variable ventilation for sensing smells, and so on.