Estimation of absorption and scattering coefficients of room surfaces by least-squares matching simulated to measured energy decay curves

摘要

When simulations of existing spaces are to be made, for example when a concert hall is subject to acoustics treatment, it is necessary to gather all input data needed for the simulation tool. Although the room geometry is not always available, but sometimes by the architect’s or acoustics consultant’s CAD model, it still could be measured on site without trouble. On the other hand, it can be very demanding to get a valid estimate of the acoustic properties of the room surfaces, mainly absorption and scattering coefficients. Nevertheless, this data is crucial for a successful simulation, often more important than the exact geometry itself.The presented method uses a least-squares method to optimize the absorption and scattering of individual room surfaces in the simulation, so that the error between simulated and measured energy decay curves for all source/receiver combinations is minimized. Advantages of this approach are the ability to address the properties of single surfaces by using ray tracing and a more detailed replication of the energy envelope of the impulse responses, especially compared to simple matching of reverberation times, which is still common practice.