臺灣博碩士論文加值系統

近岸的海洋環境噪音，大部分都是由風浪、船舶、或人類的近岸活動所影響，其中大部分近岸海洋環境噪音，主要是來自風浪所造成的碎波噪音，頻率範圍甚廣(0.5至50 kHz)，而碎波區的噪音物理機制非常複雜，且具有不同的訊號特徵。本研究中實驗地點位於高雄港旁西子灣沙灘，利用水下麥克風收集碎波噪音，並以數位式錄影機同步記錄碎波帶的運動過程。從實驗中得知，當碎波運動過程中，因波形受到不穩定而崩塌至水面同時，海水捲入大量的空氣形成氣泡團，這些氣泡團共振的結果，產生高頻聲壓值。從實驗中發現，當碎波抵達至水下麥克風上方時，頻譜上會有一脈衝訊號佈滿整個頻率，聲壓值高達120 dB。而各別頻率分析中(1k~6k Hz)，因碎波經過後殘留下的氣泡共振的影響，則2k~6k Hz聲壓值比碎波未經過水下麥克風時，相對之下有些許提升，接著對碎波噪音時間積分的結果，驗證上述碎波經過後殘留下的氣泡共振，影響高頻聲壓值的現象。而碎波聲源中，除了碎波運動過程與碎波殘留下的氣泡有所貢獻之外，碎波還有許多的因素會影響聲源的大小，例如本文中所討論的碎波週期與碎波高度，從這兩個研究結果中發現，當碎波週期越長時，而碎波最大聲壓值也會相對變大；而在碎波高度中，碎波高度越大時，碎波最大聲壓值也會隨著波浪高度增加而變大，從這兩個結論中得知，碎波週期與碎波高度也會使得碎波噪音造成變化。

　The ocean ambient noise of coast is mainly influenced by sea waves, boats or ships, or human’s coast activities. Among them, most of the ambient noise is from the breaking wave noise caused by wind, and its frequency range is quite wide (0.5~50 kHz). The breaking wave noise mechanism of surf zone is very complex, and has a variety of signal features. In this research, the location is at the Sizih Bay near Kaohsiung Harbor. Hydrophone was used to collect the noise and the wave motion process of surf zone was recorded simultaneously with a digital video camera. It was shown from the experiment results, as the wave evolved in the surf zone, it would eventually become unstable and collapsed, so a large amount of air would be trapped in water and forming bubble clouds. The oscillating bubble cloud from breaking wave would generate high frequency sound. The results also indicated that when breaking wave reached the location hydrophone, a wide band pulse sound was generated with a level as high as 120 dB. In the analysis of each frequency (1k, 2k, 3k, 4k, 5k Hz), due to the oscillating effects air bubbles after breaking wave, the noise level at 2~5k Hz were higher as compared to that without breaking wave passing the hydrophone. The last result was also validated by the time integral of the noise energy through out the wave evolution. In addition to the process of breaking waves and residual air bubbles under breaking waves contributing to the breaking wave source, for example discussed in the study breaking wave’s period and breaking wave height, the results from these two studies found, when the longer the breaking wave period , the breaking wave SPL will be bigger with the longer the breaking wave period. And in the breaking wave height, when the breaking wave height much higher, breaking wave SPL will be much bigger too. And learned from these two conclusions , breaking wave periods and height will make the breaking waves source level caused by changes.

摘要.............................................................................. i
Abstract.........................................................................ii
目錄................................................................................iii
表目錄........................................................................... vi
圖目錄............................................................................vii
第一章 緒論....................................................................1
1.1 研究背景..................................................................1
1.2 海洋環境噪音..........................................................2
1.3 碎波與海洋環境噪音..............................................5
1.3.1 碎波物理機制.......................................................5
1.3.2碎波噪音相關文獻................................................8
1.4 研究目的.................................................................10
1.5本文架構...................................................................11
第二章 研究方法............................................................12
2.1 聲音的訊號處理......................................................12
2.1.1 傅立葉轉換...........................................................12
2.1.2 短時傅立葉轉換...................................................15
2.1.3 取樣定理...............................................................15
2.2 資料統計...................................................................16
2.2.1 回歸分析................................................................16
2.2.2 相關係數.................................................................17
2.3 訊號分析流程............................................................19
第三章 實驗架構與方法..................................................21
3.1 實驗描述.....................................................................21
3.2 儀器介紹..........................................................……...22
3.3 儀器配置.....................................................................26
3.4 儀器架設.....................................................................27
3.4.1 波浪觀測方法..........................................................29
3.4.2 水下聲音量測方法..................................................29
3.5 系統校正......................................................................30
第四章 結果與討論............................................................32
4.1噪音特徵之分析............................................................32
4.2.1碎波時頻譜.................................................................32
4.2.2碎波運動過程與頻譜變化.........................................34
4.2.3 各頻率之分析…........................................................36
4.2.4碎波聲壓值積分比較….............................................36
4.2碎波噪音與近岸海洋環境音.........................................37
4.2.1碎波帶與非碎波帶噪音比較………..………............37
4.2.2碎波噪音與碎波背景值之比較………….…….........40
4.3碎波噪音與波浪週期相關性比較..................................42
4.3.1碎波長、短週期積分比較...........................................44
4.4碎波噪音與碎波高度……..............................................45
4.4.1碎波高度與碎波聲壓值機率分佈...............................47
第五章 結論與建議...............................................................49
5.1 結論.................................................................................49
5.2 建議.................................................................................51
參考文獻................................................................................52

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