微穿孔板吸声体的准确理论和设计

General theory and design of microperforated-panel absorbers

提出以等效电路的为基础的微穿孔板吸声体的准确理论。吸声体的特性参数是板的相对声阻r，穿孔直径d和共振频率f0，后二者合成穿孔板常数，它与r决定微穿孔板吸声体的结构和频率特性。吸声频带半宽△f／f0的最大值为（4／π）tan－1（1＋r），这是k值趋近于零时的极限，只要k小于1，相差也不大，这时空腔厚度接近四分之一波长。可见r值大时，带宽可达到极为可观的程度．k值大时，吸收带宽大为降低，同时空腔节厚度将成为比波长小得多的值。文中讨论微穿孔极吸声体的一般特性。

Abstract: A general theory of microperforated absorber is proposed on the basis of eguivalent circuit. The characteristic parameters of the absorber are its relative acoustic resistance r, the diameter d of the perforations and the resonance freguency f0, the later two form the perforate constant which, together with r. decides the structure and characteristics of the microperforated absorber. The maximum value of the absorber. band width Δf/f0 is (4/π) tan-1 (1 + r) as k approaches zero. and it does not change much as far as k is less than one, and the cavity depth is nearly a quarter wave length of the resonance frequency. For large values of k, the absorption band narrows down significantly and the cavity depth repuired becomes a small fraction of the wavelength. The properties of the microperforate absorber are discussed.