TY - CHAP A1 - Martens, William L. A1 - Herder, Jens T1 - Perceptual criteria for eliminating reflectors and occluders from the rendering of environmental sound T2 - 137th Regular Meeting of the Acoustical Society of America and the 2nd Convention of the European Acoustics Association N2 - Given limited computational resources available for the rendering of spatial sound imagery, we seek to determine effective means for choosing whatcomponents of the rendering will provide the most audible differences in the results. Rather than begin with an analytic approach that attempts to predict audible differences on the basis of objective parameters, we chose to begin with subjective tests of how audibly different the rendering result may be heard to be when that result includes two types of sound obstruction: reflectors and occluders. Single-channel recordings of 90 short speech sounds were made in an anechoic chamber in the presence and absence of these two types of obstructions, and as the angle of those obstructions varied over a 90 degree range. These recordings were reproduced over a single loudspeaker in that anechoic chamber, and listeners were asked to rate how confident they were that the recording of each of these 90 stimuli included an obstruction. These confidence ratings can be used as an integral component in the evaluation function used to determine which reflectors and occluders are most important for rendering. KW - audio rendering KW - first-order reflection KW - human perception KW - level of detail KW - occluder KW - sound spatialization resource management Y1 - 1999 PB - Acoustical Society of America, European Acoustics Association CY - Berlin ER - TY - CHAP A1 - Martens, William L. A1 - Herder, Jens A1 - Shiba, Yoshiki T1 - A filtering model for efficient rendering of the spatial image of an occluded virtual sound source T2 - 137th Regular Meeting of the Acoustical Society of America and the 2nd Convention of the European Acoustics Association N2 - Rendering realistic spatial sound imagery for complex virtual environments must take into account the effects of obstructions such as reflectors and occluders. It is relatively well understood how to calculate the acoustical consequence that would be observed at a given observation point when an acoustically opaque object occludes a sound source. But the interference patterns generated by occluders of various geometries and orientations relative to the virtual source and receiver are computationally intense if accurate results are required. In many applications, however, it is sufficient to create a spatial image that is recognizable by the human listener as the sound of an occluded source. In the interest of improving audio rendering efficiency, a simplified filtering model was developed and its audio output submitted to psychophysical evaluation. Two perceptually salient components of occluder acoustics were identified that could be directly related to the geometry and orientation of a simple occluder. Actual occluder impulse responses measured in an anechoic chamber resembled the responses of a model incorporating only a variable duration delay line and a low-pass filter with variable cutoff frequenc KW - audio rendering KW - first-order reflection KW - human perception KW - occluder Y1 - 1999 PB - Acoustical Society of America, European Acoustics Association CY - Berlin ER -