Pressure and intensity: a word about measuring sound

Provided that the perception of sound is subjective, sound pressure is commonly measured in decibels on a scale where our hearing threshold ranges from zero to about one hundred thirty.

It presents a plethora of sounds that we perceive as: calm (20dB), deconcentrating(40 dB), bothersome (80 dB) or that cause pain (120 dB).

The following visualisation could prove helpful in understanding this progression better and simplifying these concepts.

Visualisation produced by Francesco Scomazzon

When comparing sound pressure (dB) with sound intensity or power (watt), it is evident how a change from 40 dB to 50 dB doesn’t involve a linear progression but rather an exponential one. Thus, the logarithmic scale is useful to count only the power of 10.