衝剪機械於金屬板材加工過程中會產生高強度衝擊性噪音，為金屬製造業常見之物理性危害。作業人員長期暴露於高噪音環境，可能增加噪音性聽力損失及相關健康風險。製造業為職業病通報較頻繁之產業，其中噪音性聽力損失占有相當比例，顯示製造現場高噪音暴露問題仍有持續改善之必要。 本研究以衝剪機械加工鋼板材所產生之噪音為研究對象，探討不同板材幾何參數、衝剪噸數及隔音罩設置條件下之聲壓特性並進行頻帶與降噪效果分析。研究量測隔音罩內部與外部之等效連續 A 加權聲壓級（LAeq）及 Z 加權 1/3 倍頻程頻帶特性，並依頻帶能量分布將頻率範圍區分為低頻（≤ 125 Hz）、中頻（160–800 Hz）及高頻（≥ 1000 Hz）三個頻帶，作為頻帶整合與降噪效果分析之基礎。統計分析運用 Wilcoxon 符號等級檢定評估隔音罩內外量測條件下之降噪效果，並以 Welch ANOVA、Games-Howell 事後比較及多元線性迴歸分析，探討板材厚度、面積及材質等因素與聲壓表現之關聯性。 研究結果顯示隔音罩對衝剪製程噪音具有明顯降噪效果，於 200T、260T 及 350T 條件下降噪效果達統計顯著水準。頻帶分析結果顯示隔音罩於不同頻率區間之降噪表現並不一致，整體而言以中頻區間降噪效果較為明顯，高頻區間次之，低頻區間則相對不易抑制，顯示隔音罩降噪效果具有頻帶依賴性。迴歸分析結果顯示，不同噸數條件下板材幾何參數對外部聲壓之解釋能力有所差異，其中 260T 條件下板厚與外部聲壓呈現較明顯關聯，推測可能與板厚對衝剪負荷、材料破斷行為及其聲源特性之影響有關。 綜合而言，本研究透過聲壓量測、1/3 倍頻程頻帶分析、頻帶整合及統計方法，建立衝剪製程噪音特性與隔音罩降噪效果之評估流程。研究結果可作為金屬製造業進行衝剪噪音診斷、隔音罩設計改善及工程控制措施規劃之參考，以降低作業環境噪音暴露並提升職場安全衛生管理成效。;Punching machines generate high-intensity impact noise during metal sheet processing and are a common physical hazard in the metal manufacturing industry. Long-term exposure to high-noise environments may increase the risk of noise-induced hearing loss and related health risks among workers. Manufacturing is one of the industries with relatively frequent occupational disease reports， and noise-induced hearing loss accounts for a considerable proportion of such cases， indicating the continued need to improve high-noise exposure conditions in manufacturing workplaces. This study investigated the noise generated during steel sheet processing by punching machines， focusing on sound pressure characteristics， frequency-band distribution， and noise reduction performance under different sheet geometric parameters， punching tonnage conditions， and acoustic enclosure conditions. Noise measurements were conducted during the punching process to obtain the equivalent continuous A-weighted sound pressure level (LAeq) inside and outside the acoustic enclosure， as well as Z-weighted one-third-octave-band characteristics. Based on the frequency-band energy distribution， the frequency range was divided into three bands: low frequency (≤ 125 Hz)， mid frequency (160–800 Hz)， and high frequency (≥ 1000 Hz). These frequency bands served as the basis for subsequent band integration and noise reduction analysis. The Wilcoxon signed-rank test was used to evaluate the noise reduction effect under the measurement conditions inside and outside the acoustic enclosure， while Welch ANOVA， Games–Howell post hoc comparison， and multiple linear regression analysis were applied to examine the relationships between sound pressure levels and factors such as sheet thickness， sheet area， and material type. The results showed that the acoustic enclosure had a significant noise reduction effect on punching process noise， and the noise reduction effects under the 200T， 260T， and 350T conditions were statistically significant. Frequency-band analysis indicated that the noise reduction performance of the enclosure varied across frequency ranges. Overall， the mid-frequency band exhibited the most evident noise reduction effect， followed by the high-frequency band， while the low-frequency band was relatively difficult to attenuate， demonstrating the frequency-band-dependent characteristics of the enclosure’s noise reduction performance. The regression analysis further showed that the explanatory power of sheet geometric parameters for external sound pressure levels differed among punching tonnage conditions. In particular， under the 260T condition， sheet thickness showed a more evident association with external sound pressure levels， which may be related to the influence of sheet thickness on punching load， material fracture behavior， and the corresponding source characteristics. In summary， this study established an evaluation procedure for characterizing punching process noise and assessing the noise reduction performance of an acoustic enclosure through sound pressure measurement， one-third-octave-band analysis， frequency-band integration， and statistical methods. The findings may serve as a reference for noise diagnosis， acoustic enclosure design improvement， and engineering control planning in metal manufacturing workplaces， thereby reducing occupational noise exposure and improving occupational safety and health management.
