In a recent work by the authors, an optimal sound absorber with a compact scale consisting of multiple inhomogeneous Helmholtz resonators with extended necks (HRENs) was designed and demonstrated for effective sound absorption in a prescribed frequency range. The development of HREN-based absorber provides a promising potential for sound absorption in a compact dimension. The present study aims to line the compact optimal absorber in a circular duct for noise attenuation. A rigid duct with the same configuration is fabricated for comparison. The acoustic performances of the lined duct and the rigid duct are experimentally evaluated by using two linear microphone arrays in an anechoic chamber. Two types of noise sources are considered: a point sound source and a rotating propeller. The experimental results reveal that a significant noise reduction is achieved by the lined duct for both the point source and the propeller noise source in the target frequency range when comparing to the rigid duct.

在作者最近的工作中，设计并展示了一种紧凑的最佳吸声器，该吸声器由多个不均匀的带有扩展颈的Helmholtz谐振器（HREN）组成，并在规定的频率范围内得到了有效的吸声。基于HREN的吸声器的发展为紧凑尺寸的吸声提供了广阔的前景。本研究的目的是在圆形管道中排列紧凑型最佳吸收器，以降低噪声。为了进行比较，制造了具有相同构造的刚性导管。通过在消声室内使用两个线性麦克风阵列，对内衬管和刚性管的声学性能进行了实验评估。考虑两种类型的噪声源：点声源和旋转螺旋桨。