The International Research Fellowship Program enables U.S. scientists and engineers to conduct nine to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad.
This award will support a twelve month research fellowship by Dr. Jonathan Rathsam to work with Dr. Boaz Rafaely at Ben-Gurion University of the Negev in Beer-Sheva, Israel.
Computer based sound field simulations help identify optimal acoustical designs for theaters, auditoriums, and other acoustically critical spaces. Simulations require as input the acoustical absorption of room surfaces, which is an elusive quantity. Instead of using measured in situ (on location) data, designers generally look up previously compiled absorption data measured under standard laboratory conditions. In situ measurement conditions often differ appreciably from laboratory measurement conditions in terms of incident sound field type, sample mounting condition, and sample size. The PI has proposed the use of a spherical microphone array to make in situ absorption measurements more accessible and practical, resulting in more accurate sound field simulations. The procedure uses spherical deconvolution to decompose the sound pressure distribution across a microphone array into incident plane wave components. Spatial and temporal filtering of these components isolates direct energy and first-order reflected energy from surfaces of interest. Substituting these energy terms into the appropriate wave propagation model yields each surface's acoustical absorption. The project coincides with the opening of Ben-Gurion University's new anechoic chamber, which will be used to validate the proposed technique.
The collaboration combines the host's microphone array expertise with the PI's expertise in reflection and absorption in architectural acoustics. This investigation will develop a novel and potentially improved technique for measuring acoustical absorption of wall and boundary surface materials. The technique may also be applied to quantify the acoustic performance of environmental materials and surfaces, such as traffic noise barriers and road surfaces.
