為量測吸音材料於水中的聲學特性，本研究使用充水阻抗管，以三參數校正法進行校正，可以作為水體檢驗與量測試片的方法。並且自行研發加壓系統，對管內環境進行加壓，以便瞭解吸音材料於不同水深下的聲學特性。
為驗證實驗的可重複性，於同一天內與不同天進行吸音材與鋼片的量測，比較實驗結果可發現，同一天進行量測的吸音材反射係數幾乎重合，而不同天量測的結果，則有微小的誤差。推測是環境溫度、水質、試片擺放位置差異所造成。但是當測試材料換成鋼片時，發現量測結果沒有重複性；推測原因為加壓的充水阻抗管中仍有微小氣泡附著於鋼片上，影響實驗結果。
本文實驗進行了橡膠多孔性材質的吸音試片量測，試片厚度分別為25 mm、50 mm、75 mm，且分別於1 Patm、4 Patm、8 Patm三種壓力條件下進行量測與比較，希望藉此瞭解橡膠多孔性材質於不同厚度與壓力下的聲學特性。試驗結果顯示試片的聲波反射係數與試片厚度與水中壓力之間並無明顯關係，但75 mm的試片存在較低的反射係數平均值，且25 mm與75 mm的試片於各壓力條件下的反射係數趨勢較相近。
本研究所採用的試片為橡膠多孔性材質，此材質於不同製程下，存在不同的腔室大小，且其腔室受到擠壓變形，容易出現不穩定的狀態。本文旨在建立一套研究材料於不同水壓下之聲學特性的量測系統，藉由此系統找出最合適的水中吸音材料。

This study develops a closed water-filled impedance tube with a pressurized system to measure the acoustic characteristics of underwater sound-absorbing materials. Experi-ments are conducted using a three-parameter calibration method to calculate the reflec-tion coefficient and acoustic impedance of the materials. To verify the repeatability of the experiment, measurements are taken on the same day and on different days. The re-sults indicate that the rubber porous material sample has the highest repeatability, but the steel sample has the worst repeatability, probably because tiny bubbles are attached to the steel sample during the pressurization process. In addition, experiments are con-ducted for 25-, 50-, and 75-mm-thick rubber samples under different pressure condi-tions. Although no obvious relationship between the reflection coefficients and the sam-ple thickness as well as the water pressure is observed; however, at higher pressure, the reflection coefficient of the 75-mm sample is lower. The samples used in the study are still in the experimental stage; therefore, different production procedures have chambers of different sizes, which are unstable under various pressure conditions. In the future, this system can be used to measure the properties of different materials under various pressure conditions and thus to determine materials that are stable under high pressure and have a low reflection coefficient.

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