Numerical simulation of the laboratory measurement of sound transmission loss in rectangular test rooms is realized up to high frequency bands, using the fast multipole boundary element method. Setting membrane materials as reference samples, numerical results with fine and simplified room models are validated in comparison with measured and theoretical values. In addition to the sound-pressure-based method, another sound-intensity-based method is numerically simulated. It is demonstrated that the former method overestimates transmission loss at low frequency bands, while the latter method gives the values in relatively good accordance with theoretical ones.
