Answer to Question #79654 in Physics for Jynsur Paslein

Question

Why do we measure loudness in terms of intensity level instead of the absolute value of intensity ?

Answer 1

Loudness is a perceptual response to the physical property of intensity. As a general rule the larger the amplitude, the greater the intensity, the louder the sound.
The dynamic range of human hearing and sound intensity spans from 〖10〗^(-12) W/m^2 to 10 - 100 W/m^2. The highest sound intensity possible to hear is 10,000,000,000,000 times as loud as the quietest!
This span makes absolute values for sound intensity impractical in normal use. A more convenient way to express sound intensity is the relative logarithmic decibel scale with reference to the lowest human hearable sound - 〖10〗^(-12) W/m^2 (0 dB).