Development of techniques for visualization and auralization of sound and vibration for acoustic research and education

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In this study, the methods for visualization and auralization of various kinds of acoustic and vibration phenomena which can not be directly seen or heard have been investigated for the research and education in environmental acoustics.(1) Visualization of wave phenomena by physical experimentsTo visualize various kinds of wave phenomenena, sound diffraction over acoustic barriers and sound propagation in rooms with various shapes were investigated using the ripple-tank method. The results of these experiments were compared with the results obtained by numerical simulation based on FDTD methods.As the second method for physical experiment, the Kundt experiment was applied to visualize the normal modes in an acoustic tube and acoustic resonance in a closed pipe and a Helmholtz resonator. The experimental facilities have been refined for demonstration for acoustic education. By applying this experimental technique, acoustic resonance in the tread-patterns of a motor-vehicle tire and norm … More al modes in two dimensional spaces with various shapes and a passenger car were visualized.(2) Visualization and auralization of wave phenomena by numerical analyses using computerSuch basis acoustic phenomena as acoustic resonance and sound diffraction were visualized and auralized by the wave numerical analysis technique based on the FDTD method. As a tool for acoustic education, this simulation technique was named "numerical anechoic room" and its practical software has been developed.(3) 3-D sound field reproduction system for auralization of various kinds of sound fieldsIn such experimental researches as room acoustics and assessment of environmental noises, it is desirable to reproduce the sound fields under investigation in the laboratory with 3-dimensional acoustic information. As a technique to realize this condition, the "6-channel recording/reproduction technique was applied and its simulation performance has been improved in this study by developing a new microphone system and the reproduction system. As a result, a considerably high performance of sound source localization has been realized and precise 3-D sound field simulation has become possible. This technique has been applied to the following subjective experiments : 1) acoustic conditions on the stage of a concert hall for music players, 2) acoustic comfortableness in motor-vehicles (annoyance of running noise and easiness of listening to car-audio system), and 3) assessment of noisiness of traffic noises (road traffic noise, aircraft noise, Shinkansen super-express train and conventional railway train) with a variety of temporal variation characteristics. Less