臺灣博碩士論文加值系統

本研究以西元2001年5月3日到16日，亞洲海域國際聲學實驗(Asian Seas International Acoustic Experiment, ASIAEX)在南中國海的大陸棚裂區(Shelf Break)佈放垂直線陣列(Vertical Line Array, VLA)所收錄的環境噪音為探討對象，並分析其中50、100、200、400、800和1,200 Hz共6個頻率。研究結果顯示，淺海環境噪音與深度間的相依性並不顯著，至於其聲壓位準振盪，則可利用傅立葉分析來計算，並且利用水壓與溫度等水文資料來驗證分析的結果。結果發現此區域的環境噪音位準變化具有極低頻的K1和M2潮汐週期。另外本論文也探討環境噪音與頻率間的相依性，在低頻部份包括50、100與200 Hz，其成份主要貢獻是從遠船噪音而來，而較高頻為400、800和1,200 Hz主要是受到區域風影響，這部份的結論可由實驗期間通過的西馬隆(Cimaron)颱風，對高頻環境噪音位準的顯著提高得到進一步的佐證。最後本論文利用統計的方法估算在每個頻率中，環境噪音位準的機率分佈函數，發現低頻環境噪音並不受颱風影響而產生明顯變化，而高頻則深受颱風影響，其聲壓位準明顯被提高。本論文歸納出風浪影響環境噪音之門檻頻率為400 Hz。

The study is based upon the Vertical Line Array (VLA) of the Asian Seas International Acoustic Experiment (ASIAEX), dated from May 3, 2001 to May 16, 2001, in which the ambient noise was measured and the six frequencies (including 50, 100, 200, 400, 800, 1,200 Hz) were analyzed. The depth dependence of ambient noise levels in shallow water is not significant, and the fluctuations of ambient noise levels can be measured by Fourier analysis. With the similar analysis on static water pressure and temperature variation, the acoustic data has shown obvious in K1 and M2 tidal periods. The frequency dependence of ambient noise was also investigated, the lower frequency components, 50, 100, and 200 Hz, were mainly contributed from distant shipping noise, and the local wind was the dominating factor in higher frequencies such as 400, 800, and 1,200 Hz. This result was further verified by the increased levels at higher frequency due to the typhoon Cimaron during the experiment. Finally, the probability distribution function of ambient noise levels was calculated at each frequency, and was found the lower frequency ambient noise levels were not significantly affected by the typhoon as higher frequency. The threshold frequency of the ambient noise levels affected by the wind wave is about 400 Hz.

目 錄
摘要 .................................................................... i
Abstract ............................................................... ii
目錄 .................................................................... iii
圖目錄 .................................................................. vi
表目錄 .................................................................. xi
第一章 緒論 ............................................................. 1
1.1 研究背景 ............................................................ 1
1.2 文獻回顧 ............................................................ 2
1.3研究目的 .............................................................7
1.4 論文大網 ............................................................ 7
第二章 ASIAEX實驗架構 ................................................... 8
2.1實驗地點 ............................................................. 8
2.2 儀器佈放時程 ........................................................ 10
2.3 主要聲學儀器 ........................................................ 10
2.3.1接收陣列 ........................................................... 10
2.3.2 深海聲源 .......................................................... 13
2.3.3 淺海聲源 .......................................................... 15
2.2.4 拖曳式J-15-3 聲源 ................................................. 17
2.2.5 燈泡聲源 .......................................................... 17
2.4 氣象與風速 .......................................................... 18
第三章 相關理論 ...................................................................... 21
3.1 環境噪音位準轉換 .................................................... 21
3.2 取樣定理 ............................................................ 22
3.3 濾波處理 ............................................................ 23
3.4 統計理論 ............................................................ 25
3.4.1 變異數與標準偏差 .................................................. 25
3.4.2 機率密度函數 ...................................................... 26
3.4.3 偏率與尖率 ........................................................28
第四章 訊號處理 ......................................................... 30
4.1 聲音檔案格式 ........................................................ 31
4.2 三維頻譜 ...................................................................... 31
4.3 訊號前處理 .......................................................... 32
4.3.1 聲壓位準擷取 ...................................................... 33
4.3.2 聲壓位準校正 ...................................................... 34
4.4 統計分析 ............................................................ 35
4.5 水文資料處理 ........................................................ 36
4.5.1 溫度訊號 .......................................................... 36
4.5.2 水壓訊號 .......................................................... 36
4.5.3 風速資料 .......................................................... 36
第五章 結果分析 ...................................................................... 37
5.1 位準振盪分析 ........................................................ 37
5.1.1 環境噪音對時間之分析 .............................................. 37
5.1.2 水文資料 .......................................................... 45
5.2 聲壓位準與深度 ...................................................... 50
5.3 聲壓位準與頻率 ...................................................... 55
5.4 聲壓位準分佈分析 ....................................................59
第六章 結論與建議 ...................................................... 66
6.1結論.................................................................. 66
6.2 建議 ................................................................ 67
參考文獻 ................................................................ 68
附錄1 資料轉換程式 ...................................................... 70
附錄2 間隔擷取程式 ...................................................... 72
附錄3 聲壓位準校正方法 .................................................. 75
附錄4 機率分佈函數與其他統計參數 ........................................ 78
附錄5 溫度振盪分析 ...................................................... 79
附錄6 水壓振盪分析 ...................................................... 81

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