Farfield Spectrum of the Sonic Boom

The pressure spectrum of the sonic‐boom N wave is simply given by $P (ω) = (2π)−12TP(T)j1(ωT/2)$⁠, where T is the boom duration, P(T) is the pressure amplitude, and j₁(ωT/2) is a spherical Bessel function of the first kind and order. The effective acoustic period of the N wave is approximately $32$ times its duration. The present formulation is a simplification of those by Crocker and Young. The spectrum formula given by Zepler and Harel is incomplete.