Method and system for measuring the transmission quality of an audio transmission system (10). Preprocessing means (12) are present for preprocessing of an input signal (X) and an output signal (Y) to obtain pitch power densities (PPXwIKss(j)" 1'PYwrR.ss(fin) for the respective signals. Compensation means (13, 14) are provided for compensation of linear frequency response and time varying gain. Calculation means (13, 14) are present for calculation of loudness densities (LX(I)n, LY(fi,) from the compensated pitch power densities, and computation means (15, 16) are provided for computation of a score (Q) indicative of the transmission quality of the system (10) from the loudness densities. The compensation means (13, 14) comprise an iterative loop having at least three calculations of compensations, each calculation comprising one of a calculation of a compensation of linear frequency response and a calculation of a local power scaling factor.