本研究目標為設計結構薄化、吸音率寬頻化以及具有低頻噪音控制能力的吸音界面。以直圓管的理論解作為基礎，以阻抗匹配法進行吸音率的計算，並討論並聯與串聯的兩種不同管的組合型態進行寬頻化的設計。之後利用數值模擬進行不同幾何截面吸音管的吸音率計算，並進行更複雜幾何結構的吸音率計算。最後，架設聲學阻抗腔量測系統，以吸音率實驗進行與理論及模擬的驗證，並以3D列印機製作實驗試件。實驗與模擬比較之下，頻率位置皆吻合。所設計的串並聯式的寬頻化共振型吸音界面，於減少使用管數的同時，同時也減少了結構的總厚度，對於吸音結構薄化，以及從低到高頻率具有良好的寬頻化的吸音效果。

In this study, an improved acoustic broadband absorptive surface was proposed and investigated. The impedance chamber system was built to measure the absorption of the designed structure. We used the impedance matching theory to calculate the surface acoustic impedance and sound absorption for different types of tube absorbers, and numerical simulation was performed to examine the applicability of the impedance matching theory. It was found that the absorption of the absorbing tube would not change a lot by changing the cross-section shape from circular to square. The absorption peaks were caused by the resonance inside the tube and the acoustic energy was dissipated by the air viscosity. By introducing the folding tube, it was also discovered that the higher absorption peak frequency would shift if we increased the folding number. These findings were confirmed both numerically and experimentally. Lastly, we proposed an acoustic broadband absorptive surface design by combining parallel and serial tubes with foldings to save space while maintaining high absorption over a wide range of frequencies.

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