The formula for the sum of the sound pressure levels of n incoherent radiating sources is L Σ Σ = 10 log 10 ⁡ ⁡ ( p 1 2 + p 2 2 + ⋯ ⋯ + p n 2 p 0 2 ) dB = 10 log 10 ⁡ ⁡ [ ( p 1 p 0 ) 2 + ( p 2 p 0 ) 2 + ⋯ ⋯ + ( p n p 0 ) 2 ] dB .