Analysis of Multi-Exponential Decay Constant Estimation Methods (vor Ort)
* Presenting author
Abstract:
The measurement of the absorption coefficient in reverberation chambers according to the international standard ISO-354 shows a poor reproducibility between laboratories. A reason for this is a multi-exponential decay of the sound field due to a non-uniform distribution of absorption when the test specimen is inserted into the room. A previous study by Balint et al. indicates that the use of the initial decay time improves the estimated absorption coefficient compared to theoretical results. In this study, the sound field decay properties of a simplified setup in a reverberation chamber with a test-specimen uniformly covering a single room surface are investigated. An analytic model is used to calculate room impulse responses as well as the reference decay constants of all contributing modes. Based on the Schroeder integral of mentioned impulse responses, multi-exponential energy decay models are fitted using Bayesian statistics. The decay parameters are evaluated with respect to their accuracy in initial decay time estimation and sensitivity to noise. Results indicate that the Bayesian approach reliably determines the decay model and its parameters. Finally, the results are compared to the estimations of the reverberation times in accordance with ISO-354.
