Localization of reproduced sound sources

Different sound-reproduction systems (e.g. stereo, multi-channel systems, surround sound) may be distinguished by their capability to render an authentic spatial impression of the original auditory "scene". In order to study these systems, a first requirement is to have a valid and reliable procedure by which listeners can report their perception of where a sound comes from. In the literature, various procedures ranging from drawing sketches to head pointing have been suggested, many of which either lack precision, or intuitive "naturalness". Therefore, a new hand-held laser-pointing device the position of which is being read by a magnetic tracker was developed. This device permits to naturally point at the direction of the source while receiving visual feedback from a small laser-projected dot. In a first, methodological experiment, the new laser-pointing technique was evaluated in comparison with a graphical procedure in which listeners had to make a mark on a line in order to indicate, where the sound was perceived to emanate from. In a formal experiment with 11 participants, the new technique was found to be superior both in its precision (ca. 1.5 to 2 degrees), and accuracy of identifying both real and "virtual" sources. In a second experiment, the effect of head movements on the pointed angle was quantified. This technique was used in an investigation of the effect of loudspeaker directivity on the perceived direction of stereo-panned sound sources. (Center contract)