Development of an active noise control system for ventilation ducts based on directional control sources and robust control

比较了三种通风风道控制源结构：单扬声器定向声源(建议方法)、单扬声器双向声源(现有方法1)、定向声源双扬声器(现有方法2)。理论模型表明：(1)与已有方法1相比，已有方法2的反馈路径传递函数具有更大的相位滞后；(2)基于理论模型和实验结果表明，该方法与已有的单扬声器方法2具有相似的优点。

Three control source structures for ventilation ducts are compared: directional source with single loudspeaker (proposed method); bidirectional source with single loudspeaker (existing method 1); directional source with a pair of loudspeakers (existing method 2). It has been shown based on a theoretical model that (i)larger phase lag in feedback path transfer function is achieved by using the existing method 2 compared with the existing method 1. Moreover, it has been shown based on a theoretical model and experimental results that (ii) the proposed method has the similar advantage to the existing method 2 with single loudspeaker.