In order to improve the procedure for calculating the loudness of a complex sound, two changes have been made. (1) The equal loudness contours for bands of noise in a diffuse field have been approximated by straight lines in a log‐log plot. (2) The spacing of the contours have been altered to reflect the nonlinear growth that takes place in the loudness level of bands of noise when their width exceeds the critical bandwidth. The basic formula for the addition of loudness across frequency remains the same: the total loudnessStis given bySt = Sm + F(Σ S − Sm), whereSmis the loudest band andFhas the values 0.3, 0.2, and 0.15 for octave, half‐octave, and third‐octave bands.The revised procedure has the advantages that it can be described more easily and it agrees better with the available measurements on loudness level.