基于分流扬声器阵列的低频声控制

The shunt loudspeaker is a closed loop system comprised of a closed-box loudspeaker and a shunt circuit connecting to the loudspeaker terminals. Theoretically, arbitrary acoustic impedance can be achieved at the loudspeaker diaphragm by designing the shunt circuit. Due to the advantages of simple structure, small dimension and easy adjustment, the shunt loudspeaker attracted more and more attention in the control of low frequency sound in recent years. The existing research mainly focused on the normal sound absorption performance of a single shunt loudspeaker, and the investigations of the shunt loudspeaker array in low frequency sound control has just started. This project aims to establish the sound absorption model of the shunt loudspeaker array under filed incidence, the sound field model of an enclosure coupled by shunt loudspeakers, and the sound transmission model with coupled shunt loudspeakers. We will investigate the ultimate performance of shunt loudspeaker array in sound absorption, room modal equalization and sound insulation in low frequency, and explore the feasibility of applying shunt loudspeaker to reduce the sound radiation through the enclosure opening. Aiming at promoting the investigation of shunt loudspeaker array to practical application, we will strive to make the research results of this project form a new useful technology in national economy and national defense construction.

分流扬声器是在闭箱扬声器两端连接分流电路构成的回路系统，理论上可通过分流电路的设计在扬声器振膜处实现任意形式的声阻抗，具有结构简单、几何尺度小且便于调节的优点，近年来在低频声控制领域受到了越来越多的关注。已有研究主要集中在单个分流扬声器的低频正入射吸声特性，对分流扬声器阵列用于低频声控制的研究刚刚起步。本项目拟建立分流扬声器阵列混响场吸声模型、分流扬声器与空间耦合的声场模型以及多个分流扬声器作用下的声传输模型，探索分流扬声器阵列在低频吸声、房间模态均衡和低频隔声方面的性能极限，探讨分流扬声器用于开口空间声辐射控制的可行性。以推动分流扬声器阵列研究走向实用为目标，本项目将力争形成一项国民经济和国防建设中切实有用的新技术。

分流扬声器将声能转化成电能进行耗散和储存，优势在于调节方便，合理设计后可实现薄型的低频吸声结构。本项目针对分流扬声器及其阵列在低频声控制中所面临的一系列重要问题展开研究，包括：分流扬声器多频吸声的设计方法、使用多个分流扬声器时间距对管道消声性能的影响、分流扬声器阵列在扩散场中吸声性能的提升手段、有限大面积分流扬声器阵列对封闭空间声场的控制机理和布放优化。通过使用简化的多共振分流电路或组合不同特性的分流扬声器这两种方法，对多个低频线谱的正入射吸声数接近1。以扩散场吸声系数最大为代价函数，对分流扬声器阵元的吸声系数和阵列布置间隔进行优化，在100 Hz和200 Hz实现了1.04和0.93的混响场吸声系数。建立闭空间有限大吸声面积的解析模型，讨论刚性壁面和地面吸声场景下的分流扬声器布放对室内声势能的影响，并针对汽车车厢研究分流扬声器阵列的降噪可行性。通过分流扬声器间距的优化和新型多共振吸声结构的设计，有效提升了管道中低频声传输的传声损失。该项目解决分流扬声器在低频声控制应用中的一系列基础问题，研究内容将有效地促进分流扬声器技术在建筑和交通领域的应用。