One point source spraying its power over an ever-larger sphere. Move the sliders and watch the intensity race through powers of ten while the decibel ladder strolls: ten times the power is +10 dB, a second source is +3 dB, double the distance is −6 dB.
Sound level L = 10·log10(I / I0)
93.96 dB
2.487 × 109 times the threshold intensity.
Sound intensity I = n·P / (4πr²)
2.4868 × 10-3 W/m²
The power spreads over a sphere of area 201.1 m².
Change from pinned level
no level pinned
Pin the level, then move a slider — this line reads the difference in decibels.
Acoustic power P500 mW
Distance r4.0 m
Identical sources n1 source
Reference intensity I0 = 1 × 10-12 W/m², the threshold of hearing · the n sources are identical and share one point, so their intensities simply add.
Each of the three buttons pins the level first, then makes its change — so the pinned readout lands on exactly +10.00, −6.02 or +3.01 dB. Pin by hand to check the same rules with the sliders.