The logarithmic decibel scale is convenient calculating sound power levels for two or more sound sources
Adding Equal Sound or Noise Power Sources
The resulting sound power when adding equal sound power sources can be expressed as:
Lwt = 10 log(n N / N0)
= 10 log(N / N0) + 10 log(n)
= Lws + 10 log(n) (1)
N = sound power (W)
N0 = 10-12 - reference sound power (W)
n = number of sources
Adding Equal Sound Power Calculator
Adding of equal sound power sources can be expressed graphically
Note! Adding of two identical sources will increase the total sound power level with 3 dB (10 log(2)).
Sound power and sound power level are often used to specify the noise or sound emitted from technical equipment like fans, pumps or other machines.
Sound measured with microphones or sensors are sound pressure.
|Number of Sources||Increase in Sound Power Level|
Adding Sound Power from Sources with different Sound Powers
The sound power level from more than one source can be calculated as
Lwt = 10 log( (N1 + N2 ... + Nn) / No) (3)
Adding two sources at different levels can be expressed graphically as
|Sound Power Level Difference between|
two Sound Sources
|Added Decibel to the Highest Sound Power Level|