Optimizing stepwise rotation of dodecahedron sound source to improve the accuracy of room acoustic measures
- 1 September 2013
- journal article
- research article
- Published by Acoustical Society of America (ASA) in The Journal of the Acoustical Society of America
- Vol. 134 (3), 2037-2048
- https://doi.org/10.1121/1.4817879
Abstract
Dodecahedron sound sources are widely used for acoustical measurement purposes as they produce a good approximation of omnidirectional radiation. Evidence shows that such an assumption is acceptable only in the low-frequency range (namely below 1 kHz), while at higher frequencies sound radiation is far from being uniform. In order to improve the accuracy of acoustical measurements obtained from dodecahedron sources, international standard ISO 3382 suggests an averaging of results after a source rotation. This paper investigates the effects of such rotations, both in terms of variations in acoustical parameters and spatial distribution of sound reflections. Taking advantage of a spherical microphone array, the different reflection patterns were mapped as a function of source rotation, showing that some reflections may be considerably attenuated for different aiming directions. This paper investigates the concept of averaging results while changing rotation angles and the minimum number of rotations required to improve the accuracy of the average value. Results show that averages of three measurements carried out at 30° angular steps are closer to actual values and show much less fluctuation. In addition, an averaging of the directional intensity components of the selected responses stabilizes the spatial distribution of the reflections.Keywords
This publication has 12 references indexed in Scilit:
- On the use of microphone arrays to visualize spatial sound field informationApplied Acoustics, 2013
- Investigations on the balloon as an impulse sourceThe Journal of the Acoustical Society of America, 2011
- The just noticeable difference of center time and clarity index in large reverberant spacesThe Journal of the Acoustical Society of America, 2010
- Investigation of the just noticeable difference of the clarity index for music, C80.The Journal of the Acoustical Society of America, 2009
- Directional CharacteristicsPublished by Springer Science and Business Media LLC ,2009
- Uncertainties caused by source directivity in room-acoustic investigationsThe Journal of the Acoustical Society of America, 2008
- A simple impulse sound source for measurements in room acousticsApplied Acoustics, 2008
- An experimental evaluation of regular polyhedron loudspeakers as omnidirectional sources of soundThe Journal of the Acoustical Society of America, 2006
- A just noticeable difference in C50 for speechApplied Acoustics, 1999
- Auditorium acoustics measures from pistol shotsThe Journal of the Acoustical Society of America, 1986