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Open Access Report on the 3rd Round Robin on Room Acoustical Computer Simulation – Part II: Calculations

In the second part of this report the calculated room acoustical parameters (ISO3382) submitted by a number of users and developers are compared with the measured data of Part I. In three phases the recording studio of the Physikalisch-Technische Bundesanstalt Braunschweig had to be modelled with an increasing number of geometrical details. The first phase with a simple model consisting of seven walls served to check the reliability of the software used and revealed for some participants some significant deviations from the expected values obtainable by applying Sabine's formula. For phase 2 and 3 the results of six programs are discussed here, some of them represented as mean values for a number of users applying the same programs. Most programs show good coincidence with the measured data, keeping track also of local variations of sources and receivers and the specified change of the curtain positions. Wave effects leading to sound fields of low modal density in the 125 Hz octave band are the reasons for higher calculation errors, because phase is not considered in the participating simulation programs. The accuracy of the absorption data, especially for the most absorbing surfaces, is crucial and determines the calculated decay times to a high degree. The increase of details in phase 3 for two diffusing areas was shown to have only little influence on the data obtained.

Document Type: Research Article

Publication date: July 1, 2005

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