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

本研究探讨了环境声学研究和教学中各种不能直接看到或听到的声学和振动现象的可视化和听觉化方法。(1)通过物理实验实现波现象的可视化为了使各种波现象可视化，采用波纹槽法研究了声音在不同形状的房间中的声障衍射和声音在不同形状房间中的传播。将实验结果与基于时域有限差分法的数值模拟结果进行了比较。作为物理实验的第二种方法，昆特实验被用于可视化声管中的正态模态和封闭管道和亥姆霍兹谐振腔中的声共振。实验设备经过改进，可用于声学教学的演示。应用该实验技术，对汽车轮胎胎面纹和标准胎面纹的声共振进行了可视化，并对不同形状的二维空间和一辆乘用车进行了实测。(2)利用计算机数值分析实现声波现象的可视化和听觉化利用基于时域有限差分法的声波数值分析技术实现了声共振、声衍射等基本声学现象的可视化和听觉化。作为一种声学教学工具，这种模拟技术被命名为“数值消声室”，并开发了实用软件。在室内声学和环境噪声评价等实验研究中，需要在实验室中以三维声学信息再现所研究的声场。为了实现这一条件，本研究采用了“6通道录音/再现”技术，并通过开发一种新的传声器系统和再现系统来提高其模拟性能。从而实现了相当高的声源定位性能，使精确的三维声场模拟成为可能。该技术已应用于以下主观实验：1)音乐厅舞台上音乐播放器的声学条件，2)机动车辆的声学舒适性（行驶噪声的烦恼性和汽车音响系统的易听性），3)交通噪声（道路交通噪声，飞机噪声，新干线超快列车和常规铁路列车）的噪声度具有各种时间变化特征的评价。少

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