臺灣博碩士論文加值系統

近年來，虛擬實境(VR)技術的進步促進了3D音效技術的發展。然而，頭戴式顯示器必須與耳機搭配使用，而耳機除了配戴不易與衛生問題。為了有效地解決這些問題並且提升用戶體驗，本研究引入了一項將頭戴式顯示器與微型揚聲器結合的新設計，目標為利用此一裝置建構虛擬聽覺空間。為達成此一目標，本研究提出了一個頭戴式顯示器到耳道之間的轉移函數，即虛擬實境相關轉移函數(VR-to-ear-canal transfer function, VRTF)，以建構虛擬聽覺聲場，然後研究了如何利用微型揚聲器播放3D音效。首先，使用有限元素法(FEM)模擬分析頭相關轉移函數(HRTF)的數據庫，並與實驗量測的結果進行比較。接著使用有限元素法模擬分析VRTF，並進行實驗量測，然後與HRTF數據庫結合以實現VR頭戴式顯示器的虛擬聽覺重放技術。最後，使用CAPZ模型估計HRTF與VRTF，以簡化虛擬聽覺重放的訊號處理過程。

The progress in virtual reality (VR) has enabled further application of three-dimensional (3D) audio technology. However, head-mounted displays must be used with headphones, engendering personal hygiene concerns. To solve these problems and enhance user experience, this study introducess a new design for a head-mounted display equipped with microspeakers for creating a virtual auditory space. To achieve signal processing in VR auditory displays, we derived a VR-to-ear-canal transfer function (VRTF) to create virtual auditory spaces and then investigated how to relay 3D audio between human ears and the microspeakers inside the head-mounted display. First, a head-related transfer function (HRTF) database was calculated using the finite element method (FEM) and compared with the function obtained in experiments. Second, VRTFs were calculated using the FEM, measured in experiments, and combined with the HRTF database to achieve signal processing in VR auditory displays. Finally, the CAPZ model of HRTFs and VRTFs was measured to simplify signal processing in VR auditory displays.

摘要 II
Abstract III
目錄 IV
圖目錄 VIII
表目錄 XIII
第一章 緒論 1
1.1 研究動機 1
1.2 文獻回顧 2
1.2.1 聲源定位 2
1.2.2 三度空間聲音之合成 4
1.3 研究方法與目的 7
1.4 全文架構 8
第二章 研究理論 9
2.1 聲波的散射(scattering)與繞射(diffraction) 9
2.2 聽覺定位 10
2.2.1 Interaural Time Difference(ITD) 10
2.2.2 Interaural Level Difference(ILD) 11
2.2.3 耳廓效應 13
2.2.4 頭相關轉移函數 14
2.3 虛擬聽覺重放之數位訊號處理 15
2.3.1 FIR與IIR濾波器 15
2.3.2 共聲學極點/零點模型(Common-Acoustical-Pole and Zero Model, CAPZ) 17
2.4 有限元素法 20
第三章 剛性球的散射聲場 21
3.1 剛性球的散射聲場解析解 21
3.2 剛性球的HRTF解析解 25
3.3 剛性球的HRTF數值解 27
第四章 HRTF之數值分析 36
4.1 聲學仿真人偶 36
4.2 HRTF特性分析 40
4.2.1 有限元素法模擬 40
4.2.2 耳道長度分析 42
4.2.3 HRTF特性探討 43
第五章 VRTF之數值分析 47
5.1 頭戴式顯示器 47
5.2 虛擬實境相關轉移函數(Virtual-Reality-To-Ear-Canal Transfer Function, VRTF) 50
5.3 VRTF特性分析 51
5.3.1 有限元素法模擬 51
5.3.2 近場HRTF 52
5.3.3 VRTF特性探討 55
第六章 HRTF與VRTF之量測實驗 57
6.1 實驗場地 57
6.2 實驗器材介紹 58
6.3 實驗流程 62
6.4 實驗結果與討論 66
6.4.1 HRTF實驗結果 66
6.4.2 VRTF實驗結果 74
第七章 VR之虛擬聽覺重放 77
7.1 雙耳訊號合成 77
7.2 最小相位近似 78
7.3 共聲學極點/零點模型近似(CAPZ) 80
7.4 虛擬聽覺重放 85
7.4.1 實驗流程 85
7.4.2 實驗結果 85
第八章 結論 87
8.1 結論 87
8.2 未來工作 89
參考文獻 91

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