Measuring Sound Intensity
Physical measure: energy delivered to a unit surface in unit time: Watts/m2
Our perception of loudness is not proportional with the physical measure
(increasing 8 times the energy we hear it only 2 times louder)
Our ear has a very wide range of sensitivity:
- the faintest sounds that can be heard
10-12 W/m2 (variations of pressure of about one billionths of an atmosphere)
A logarithmic scale for characterizing our loudness perception: decibels (dB) (reflects the loudness sensation) - an increase of 10 times in the power, increases this measure by adding 10.
- the hearing threshold : 1dB