TY - JOUR 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 JF - The Journal of the Acoustical Society of America 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 frequency. KW - virtual environment Y1 - 1999 U6 - https://doi.org/10.1121/1.425354 VL - 105 IS - 2 SP - 980 ER - TY - JOUR A1 - Martens, William L. A1 - Herder, Jens T1 - Perceptual criteria for eliminating reflectors and occluders for efficient rendering of environmental sound JF - The Journal of the Acoustical Society of America Y1 - 1999 U6 - https://doi.org/10.1121/1.425349 VL - 105 IS - 2 SP - 979 ER - TY - CHAP A1 - Cohen, Michael A1 - Herder, Jens A1 - Martens, William T1 - Panel: Eartop computing and cyberspatial audio technology T2 - IEEE-VR2001: IEEE Virtual Reality KW - VSVR Y1 - 2001 SN - 0-7695-0948-7 SP - 322 EP - 323 PB - IEEE CY - Yokohama ER - TY - JOUR A1 - Amano, Katsumi A1 - Matsushita, Fumio A1 - Yanagawa, Hirofumi A1 - Cohen, Michael A1 - Herder, Jens A1 - Martens, William A1 - Koba, Yoshiharu A1 - Tohyama, Mikio T1 - A Virtual Reality Sound System Using Room-Related Transfer Functions Delivered Through a Multispeaker Array: the PSFC at the University of Aizu Multimedia Center JF - TVRSJ N2 - The PSFC, or Pioneer Sound Field Controller, is a DSP-driven hemispherical loudspeaker array, installed at the University of Aizu Multimedia Center. The PSFC features realtime manipulation of the primary components of sound spatialization for each of two audio sources located in a virtual environment, including the content (apparent direction and distance) and context (room characteristics: reverberation level, room size and liveness). In an alternate mode, it can also direct the destination of the two separate input signals across 14 loudspeakers, manipulating the direction of the virtual sound sources with no control over apparent distance other than that afforded by source loudness (including no simulated environmental reflections or reverberation). The PSFC speaker dome is about 10 m in diameter, accommodating about fifty simultaneous users, including about twenty users comfortably standing or sitting near its ``sweet spot,'' the area in which the illusions of sound spatialization are most vivid. Collocated with a large screen rear-projection stereographic display, the PSFC is intended for advanced multimedia and virtual reality applications. KW - audio signal processing, audio telecommunications KW - auralization KW - calm technology KW - directional mixing console KW - multichannel sound reproduction KW - room-related transfer functions KW - roomware KW - sound localization KW - virtual conferencing environment Y1 - 1998 U6 - https://doi.org/10.18974/tvrsj.3.1_1 VL - 3 IS - 1 SP - 1 EP - 12 PB - J-STAGE 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 - 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 - JOUR A1 - Cohen, Michael A1 - Herder, Jens A1 - L. Martens, William T1 - Cyberspatial Audio Technology T1 - available in Japanese as well - Acoustical Society of Japan, Vol. 55, No. 10, pp. 730-731 JF - The Journal of the Acoustical Society of Japan (E) N2 - Cyberspatial audio applications are distinguished from the broad range of spatial audio applications in a number of important ways that help to focus this review. Most significant is that cyberspatial audio is most often designed to be responsive to user inputs. In contrast to non-interactive auditory displays, cyberspatial auditory displays typically allow active exploration of the virtual environment in which users find themselves. Thus, at least some portion of the audio presented in a cyberspatial environment must be selected, processed, or otherwise rendered with minimum delay relative to user input. Besides the technological demands associated with realtime delivery of spatialized sound, the type and quality of auditory experiences supported are also very different from those associated with displays that support stationary sound localization. Y1 - 1999 U6 - https://doi.org/10.1250/ast.20.389 N1 - available in Japanese as well - Acoustical Society of Japan, Vol. 55, No. 10, pp. 730-731 VL - 20 IS - 6 SP - 389 EP - 395 ER -