Work out sound intensity level (db) instantly with clear inputs, formula shown and shareable results.
The decibel scale compresses the enormous range of audible intensities logarithmically: L = 10 log10(I/I0). An intensity of 1 mW/m2 against the 1e-12 reference is 90 dB, a billion times the threshold. Every 10 dB is a tenfold intensity increase but sounds only about twice as loud subjectively.
Intensity level
L = 10 log10(I / I0)
Reference
I0 = 1e-12 W/m2, the hearing threshold
Loudness perception follows roughly a power law with exponent 0.3, so a tenfold intensity change gives about a doubling in judged loudness.
No. It is always a ratio against a stated reference, which is why sound levels are strictly dB re 1e-12 W/m2.