Study of the active sound field control in building acoustics

本研究项目旨在探讨主动噪声控制技术的原理及其在建筑声学中的应用，并取得了以下成果：(1)主动吸声：作为主动控制吸声的基本应用，研究了利用一个扬声器、两个参考麦克风和“Filtered-X”LMS算法产生以吸声边界终止的一维声场的方法。(2)主动隔声：为了研究主动控制技术对提高建筑墙体隔声效果的有效性，进行了自适应前馈控制的基础实验。结果表明，双层墙体的隔声缺陷可以得到弥补，并且开口的声音传播可以减少。(3)风管系统的主动降噪：自适应前馈控制作为一种降低暖通空调风管系统噪声的方法，在多室风管中得到了更多的应用。将试验结果与有限元计算结果进行了比较，两者吻合较好。(4)声强主动控制：对声强作为噪声主动控制参考量的方法进行了理论和实验研究。(5)主动控制在通风系统中的应用：通过比例模型试验，探讨了噪声主动控制技术在某电站通风系统中的应用。(6)主动模式控制：为了降低封闭环境中低维模式引起的声压，通过边界元计算和比例模型实验验证了主动控制的应用。(7)产生安静区：为了在嘈杂的房间中产生局部的安静区，实验检验了主动控制的有效性。(8)管道系统振动主动控制：针对结构振动问题，采用含水管道系统进行了实验。研究结果表明，采用主动控制技术可以有效地降低振动在管道系统中的传播和由此产生的噪声辐射。少

This research project has been planned to investigate the principle of active noise control technology and its applicabilities in building acoustics and the following results have been obtained.(1) Active sound absorption : As a basic application of active control to sound absorption, the way of producing an 1-dimensional sound field terminated with an absorptive boundary by using a loudspeaker, two reference microphones and the "Filtered-X" LMS algorithm has been studied.(2) Active sound insulation : To investigate the effectiveness of the active control technology for increasing the sound insulation of building walls, basic experiments using the adaptive feedforward control have been conducted. As a result, it has been found that sound insulation deficiencies of double walls can be recovered and the sound transmission from the openings can be reduced.(3) Active noise reduction in duct systems : As a method of reducing noises in HVAC duct systems, the adaptive feedforward control was … More applied to a multi-chamber duct. The effect obtained by the experiment was compared with the FEM calculation results, and a fairly good accordance was found between them.(4) Active control using sound intensity : The method using sound intensity as the reference quantity in active noise control was investigated theoretically and experimentally.(5) Application of active control to air-ventilation system : The application of the active noise control technology to air-ventilation system in a electric power station was examined by a scale model experiment.(6) Active mode control : To reduce the sound pressure caused by low dimensional modes in closed enclosures, the application of active control was examined by BEM calculation and scale model experiment.(7) Production of quiet zone : To produce a localized quiet zone in noisy rooms, the effectiveness of the active control was examined experimentally.(8) Active vibration control in pipe system : Regarding the structural vibration problems, an experiment was conducted using a pipe system containing water. As a result, it has been found that the vibration propagation in pipe system and resulting noise radiation can be reduced by the active control technology. Less