Tue, 01/22/2013 - 5:00pm - 6:00pm
CCRMA Classroom, The Knoll 2nd floor, Rm 217
Multi-channel spherical loudspeakers became popular for control of directional radiation. They have been introduced in shapes of cubes, dodecahedra, or higher-order discrete representations of spheres. In this presentation a spherical source with a partial Gaussian distribution of 28 channels is presented. With sequential measurements and rotation of the sphere a radiation of effectively 23rd order of spherical harmonics is obtained, as long as the acoustic conditions are time-invariant. In auralization, this source can reproduce musical instruments, for example, or it can radiate directional Dirac functions (sound pointer) for detection and analysis of room reflections. Filter design and various applications are discussed as well as an approach for measurement of binaural room impulse responses reciprocally. In the latter example, the spherical loudspeaker acts as an HRTF radiator. For all applications in auralization, rotations of the source and the listener such as head orientation movements can be taken into account by multi-channel real-time convolution and dynamic filters. The theoretical background, the mechanical solution and the software components are discussed and evaluated with regard to challenges, performance, and limitations.
Michael Vorländer is Professor at RWTH Aachen University, Germany. He is active in national and international organizations. He was President of the EAA in the term 2004 – 2007 and now serves as President of the International Commission for Acoustics, ICA, for the term 2011-2013. He was awarded the Stephens Medal of the IoA in 2005, Fellow of ASA in 2006, and the Caracola of the Spanish Acoustical Society in 2009 and Honorary Member of the Polish Acoustical Society in 2012. His actual research is on auralization and acoustic virtual reality in various applications in architectural acoustics and environmental noise.