| [摘要] |
|
擴散音場是古典餘響理論的基本假設，但在實際的廳堂中，所形成的音場並非完全或近似 |
| 完全的擴散。而為音響性能評估指標之一的雙耳相關係數(IACC)也能反應反射於方向上的 |
|
分佈。但擴散音場是否代表一個適合做為表演的場所，設計上如何定量使用擴散材或如何 |
| 在設計中估算音響性能，都值得再探討。 |
|
基於上述之因素，本文乃針對廳堂中的擴散行為做探討。首先是針對廳堂音響有關擴散的 |
|
進展作整理，其中包括對於廳堂室內音場的擴散性、擴散面與擴散反射以及擴散材在廳堂 |
|
音響設計上的運用等課題的文獻整理，在這個部分當中根據相關音響理論的觀點可以得知 |
| 平面形式的選擇依據以及較常用的幾種擴散材的擴散特性。 |
|
在瞭解一些擴散行為的相關特性之後，本研究遂以簡單矩形廳堂為測試環境，以二次剩餘 |
|
擴散材以及1/4圓弧面所組成的模矩單元作舞台、觀眾席小面積及觀眾席大面積的處理，總 |
|
計為17種配置模式，然後以麥克風接收音源之脈衝響應，進而計算與擴散性能相關之評估 |
| 指標(包括IACC、EC、TD、EDT、G、C80等)。 |
|
最後本研究即就這些評估指標作舞台擴散材配置、觀眾席擴散材配置數量及位置、測點位 |
|
置與音源及反射面距離等變因的分析，同時也將量測結果與古典理論及修正理論作比較。 |
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綜合前述之探討發現廳堂中的擴散性能主要是由平面形式與擴散材料的使用有密切的關連 |
|
性。平面形式是以矩形平面最為理想，而在材料的使用上，由量測結果的分析中，可瞭解 |
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各種配置模式之間在各個評估指標的差異性，這些結果將可作為廳堂設計時，有關音響性 |
| 能上的參考。 |
|
| [摘要] |
| Although sound diffusion has
long been recognized to be effective of |
| eliminating acoustical defects,
there is drawback for an extremely diffused |
| sound field. It is important to
achieve a balance between increasing apparent |
| source width and avoiding
excessive coloration. However, quantitative design |
| guidelines regarding
implementation of diffusive materials in concert halls |
| can rarely be found. Therefore
the current research is proposed to investigate |
| physical behaviors and
psychological aspects regarding sound diffusion in |
| music auditoria. |
| Emphases of literature were
placed upon acoustical qualities related to sound |
| diffusion, acoustical
characteristics of various kind of diffusive surfaces, |
| and current knowledge about
implementing diffusive materials in concert |
| halls. Acoustical tests in a
1:10 scale model were made regarding the |
| implementation of diffusive
surfaces in a simple rectangular hall with a seat |
| count of 360. Diffusive surfaces
were mixtures of quadratic residue sequence |
| and 1/4 cylinder. With the
maximum area of diffusive surface limited to the |
| audience ceiling, seventeen
schemes of layouts were tested. Analyses of |
| acoustical measures including
inter-aural cross correlation (IACCE and IACCL), |
| temporal diffusion (TD), echo
criteria (EC), strength factor (G), and early |
| decay time (EDT) were made for
individual receiving locations as well as for |
| the average and dispersion of
data from all receiving locations. |
| Use of diffusive surface and
splayed flat panel on the stage are effective in |
| reducing EC, TD, IACCE and IACCL
values, and diminishing the among-seat |
| differences of G and
EDT. Additional diffusive surfaces in the audience area |
| do not show apparent
improvements except TD was decreased when diffusive |
| surfaces were places on the side
walls. As Barron suggested according to |
| Lambert’s Law, Application of
diffusive surface on the ceiling would hinder |
| the sound propogation towards
the rear and result in greater G difference |
| among seats. |
| The results of the research can
provide quantitative information for refining |
| design strategies of preventing
acoustical defects yet enhancing spaciousness |
| of individual seat and
homogeneity among seats. |