No abstract

It is well known that head movements are instrumental in resolving front/back confusions in human sound localization. A mechanism for a binaural model is proposed here to extent current cross-correlation models to compensate for head movements. The algorithm tracks sound sources in the head-related coordinate system (HRCS) as well as in the room-related coordinate system (RRCS). It is also aware of the current head position within the room. The sounds are positioned in space using an HRTF catalog at 1 deg azimuthal resolution. The position of the sound source is determined through the inter-aural cross-correlation (IACC) functions across several auditory bands, which are mapped to functions of azimuth and superposed. The maxima of the cross-correlation functions determine the position of the sound source, but unfortunately, usually two peaks occur—one at or near the correct location and the second one at the front/back reversed position. When the model is programed to virtually turn its head, the degree-based cross-correlation functions are shifted with current head angle to match the RRCS. During this procedure, the IACC peak for the correct hemisphere will prevail if integrated over time for the duration of the head movement, whereas the front/back reversed peak will average out.

We present a novel, low-power and untethered pneumatic haptic device, namely the ACTIVE-Hand, for realistic and realtime 3D gaming experience. Currently, body-motion based 3D gaming systems primarily use visual feedback to provide partly immersive gaming experiences. Tactile feedback systems in Virtual Reality provide immersion with high tactile resolution, but they are expensive and difficult to setup and calibrate. The conceptually economical modular design of the ACTIVE-Hand allows easily configurable tactile feedback as per application requirements. Contrary to commercial systems like Wii TM which provide global vibrations as a proxy for synthetic tactile feedback, the ACTIVE Hand is comparably lightweight, yet scalable to meet localized tactile resolution requirements. The ACTIVEHand provides controllable pulses for dynamic virtual interactions such as pressing virtual buttons and hitting moving virtual balls. We successfully demonstrate the paradigm of dynamic tactile interactions in virtual environments through a 3D Pong game by integrating the ACTIVE-Hand with Kinect TM camera. NOMENCLATURE P i ,V i Pressure,Volume of air inside a closed pneumatic system at neutral state. d Distance of the piston away from neutral state.

Acoustics consultants have many tools in their arsenal to evaluate and design rooms and architectural elements; the computational resources available to this point have made the use of wave-propagation models impractical for the common user. Threshold acoustics has found it both useful and now computationally feasible to supplement more traditional, geometric analysis with the simulation of wave-propagation using finite-difference time-domain (FDTD). Our group has developed first-order leapfrog FDTD routines in MATLAB for simulating wave propagation in an isotropic medium in two- and three-dimenision with perfectly matched layers being the boundary condition. The placement of solid elements within the test space allows analysis of arbitrary geometries. For additional computational power, our group has utilized GPU computing clusters available through Amazon Web Services accessed directly through MATLAB. Our method is based on the simulation of an impulse response and subsequent analysis of the impulse response consistent with traditional in situ testing methods. Applications to date include analysis of the scattering behavior of acoustically shaped surfaces and evaluation of the array behavior of architectural reflector panels.

Raytracing is a simple but powerful tool in acoustics consulting because of its ability to geometrically approximate wave behavior across a large portion of the audible spectrum. The use of this method requires an understanding of the frequency-dependent interaction between sound waves and geometry, which is a wave-specific behavior that any use of ray-based approximations must consider. The limitations of these approximations may necessitate geometric modifications in a model to render credible results, or may even dictate raytracing is inappropriate for a given application. Ray-based analysis can be used for applications with a wide range of complexity, from hand-traced sketches to computational simulation for full-scale rooms. Common applications include analysis of reflector coverage, design of room shape and major room components, and impulse response simulation for analysis and auralization. Due to their efficiency and simplicity, ray methods remain indispensable in architectural acoustic analysis.