Active control of noise propagation outdoors.

目前对有源噪声控制的研究大多局限于有限的空间，如耳机、有源消声器、空调管道、卡车客舱和飞机机身。在这项研究中，探讨了在无限制空间采用主动噪声控制来降低道路交通噪声的基本概念。该方法是开发一种受控的声影，由一堵二次声源墙产生，以减少复杂区域方向上的不需要的声音。讨论了JMC的基本理论，然后是计算机模拟和实验测量。在实验中，使用三极二次声源来控制二次声源的壁面。我们的有源噪声控制系统将宽广的噪声区域控制在一个安静的空间。讨论了该方法在道路交通噪声问题中的应用。

Most of the current research on active noise control is confined to restricted spaces such as earphones, active silencers, air-conditioning ducts, truck cabins and aircraft fuselages. In this study, thc basic concepts of road traffic noise reduction by using active noise control in unconfined spaces are explored. The approach is to develop a controlled acoustic shadow, gcnerated by a wall of secondary sources, to reduce unwanted sound in the direction of a complalnt area. The basic JMC theory is considered, followed by computer modelling, and experimental measurements. In the experiments, tripole secondary sound sorces were used to control the wall of secondary sources. Wide noisy area were controlled to a quiet space by our active noise control system. The application to the road traffic noise problem was discussed.