Active noise control (ANC), with counteracting sound in exact equal magnitude and opposite phase to the noise to be controlled, is often considered as a potential solution for solving complex noise problems. However, there are both myths and challenges in its implementations. In a crowded city like Singapore, many noise sources from construction site and subway track are located very close to the residential and commercial buildings. It was suggested by few researchers that by placing suitable control speakers at the construction site (working principle of ANC), the noise from the construction site could be prevented from propagating to the surrounding buildings. Similarly, for viaduct or subway track, by placing control speakers along the viaduct or track, the noise generated by the passing trains or vehicles could be reduced based on the principle of ANC technique. However, implementation of ANC technique on these noise issues is not easy as all of these noise control problems involve multiple noise sources with complex or transient frequency spectrum in large three-dimensional/open space. Therefore, the main intention of the present paper is to discuss the current state of the art of this topic as well as to examine the potential application and limitation of the ANC technique in mitigating unwanted noise, particularly in large three-dimensional/open space and with cooperation of passive noise barrier.

中文翻译：

---

三维/开放空间中噪声屏障的主动噪声控制应用回顾：神话与挑战

有源噪声控制 (ANC) 与要控制的噪声具有完全相同的幅度和相反相位的抵消声音，通常被认为是解决复杂噪声问题的潜在解决方案。然而，在其实施过程中既有神话也有挑战。在新加坡这样一个拥挤的城市，许多来自建筑工地和地铁轨道的噪音源都位于非常靠近住宅和商业建筑的地方。少数研究人员建议，通过在施工现场放置合适的控制扬声器（ANC 的工作原理），可以防止施工现场的噪音传播到周围的建筑物。同样，对于高架桥或地铁轨道，通过沿高架桥或轨道放置控制扬声器，基于ANC技术的原理，可以减少经过的火车或车辆产生的噪音。然而，在这些噪声问题上实施 ANC 技术并不容易，因为所有这些噪声控制问题都涉及在大型三维/开放空间中具有复杂或瞬态频谱的多个噪声源。因此，本文的主要目的是讨论该主题的当前技术水平，并检查 ANC 技术在减轻不需要的噪声方面的潜在应用和限制，特别是在大型三维/开放空间和配合无源隔音屏障。在这些噪声问题上实施 ANC 技术并不容易，因为所有这些噪声控制问题都涉及在大型三维/开放空间中具有复杂或瞬态频谱的多个噪声源。因此，本文的主要目的是讨论该主题的当前技术水平，并检查 ANC 技术在减轻不需要的噪声方面的潜在应用和限制，特别是在大型三维/开放空间和配合无源隔音屏障。在这些噪声问题上实施 ANC 技术并不容易，因为所有这些噪声控制问题都涉及在大型三维/开放空间中具有复杂或瞬态频谱的多个噪声源。因此，本文的主要目的是讨论该主题的当前技术水平，并检查 ANC 技术在减轻不需要的噪声方面的潜在应用和限制，特别是在大型三维/开放空间和配合无源隔音屏障。