| [摘要] |
| 本研究以Odeon
5.0版室內音響模擬軟體及二實際廳堂之現場量測實驗，評估音源指向性對 |
|
室內樂廳音響性能之影響。在電腦模擬中，所有室內表面均為相對較大之平面；模擬之控 |
|
制變因有尺度、比例、舞台設計、側牆設計、座席區設計、音源指向性與音源朝向。討論 |
|
之音響參數為清晰度C80及早期音強指數G80。現場實測分別在365席及831席之廳堂中進行 |
|
，探討廳堂寬度、舞台立式反射版及音源朝向之影響。分別比較12面體喇叭之無指向音源 |
|
發音與近似小號之指向喇叭發音所造成之差異，指向音源為前、左、右及上（喇叭面向前 |
| 朝上30°）四種朝向狀況。 |
|
電腦模擬結果發現，音源指向性之影響明顯隨廳堂寬度增加而增大且隨廳堂尺度的增加略 |
|
為增大。在室容積5000m3，長寬比為2之模擬模型中，小號音源朝向由＋45°轉為-45°造 |
|
成之C80與G80差異約為2.5dB~3dB，當廳堂寬度由17m增加至21m時，音源朝向轉變之影響更 |
|
為明顯。側邊反射版有助於增加位於其指向方向位置處之高頻G80值，但舞台側牆展斜則無 |
|
所助益，原因是其反射音指向廳堂後部，取代原本橫越觀眾席指向廳堂二側之反射音。觀 |
|
眾席採中央低四周高之分割式設計，可有效降低音源朝向轉變造成之C80與G80變動。 |
|
現場實測結果發現廳堂寬度之影響與電腦模擬結果相符，較大而寬的廳（27m寬）因音源指 |
|
向性造成之差異比較小而窄的廳（17m寬）明顯。不連續之舞台側邊反射版（相距6m）在音 |
|
源指向廳堂左側之狀況下，可有效增加觀眾席右側之G80。音源朝上所造成之影響與音源朝 |
|
前之狀況差異不大，原因是在較小的廳中天花板高度低而較大的廳中前舞台口之圓弧反射 |
| 面與懸吊天花板反射所致。 |
|
關於音源指向性之影響仍有許多關於廳堂設計、個別樂器指向特性與主觀喜好等課題有待 |
| 後續研究探討。 |
|
| [摘要] |
| Effects of directional source on
room acoustics of rectangular chamber music |
| halls were evaluated based on
acoustical simulations using Odeon 5.0 software |
| and field measurements. For
computer simulation, all surfaces were plane and |
| relatively large. Controlling
variables included size, proportion, stage |
| layout, side-wall layouts,
seating layouts, directivity of the source, and |
| aiming direction of the sound
sources. Acoustical measure clarity (C80) and |
| early strength (G80) was used.
In a 365-seat hall and an 831-seat hall, the |
| field study examined the effects
of room width, detached side reflectors, and |
| aiming directions. A
dodecahedron speaker source was compared to a speaker |
| having the directivity similar
to a trumpet, which was aiming to the front, |
| the left, the right, and the top
(30° tilting towards the front). |
| Based on computer simulation, it
has been found that the effects of source |
| directivity significantly
increased with increasing room width and slightly |
| increased with the increasing
overall size. Inside a 5000-m3 hall with nearly |
| 1:2 width-to-length ratio,
turning a trumpet sound source between +45° and -45 |
| ° making 2.5dB~3dB difference on
both C80 and G80. The effect became |
| significantly large when the
room width was increased from 17 m to 21 m. |
| Lateral reflectors were useful
for enhancing high frequency G80 for seats that |
| located opposite to the aiming
direction but splayed front side-walls were |
| useless because the reflections
were directed towards the end of the hall |
| instead of crossing to the other
side of the hall. Subdividing the hall with |
| a lower centerpiece and higher
perimeters was effective in reducing the |
| difference due to turning aiming
directions. |
| The field measurement agreed
with the computer modeling regarding the |
| importance of room width. The
larger and wider hall (27-m wide) caused a |
| much higher directional
difference than the smaller and narrower hall (17-m |
| wide). Detached side reflectors
(6 m apart from each other) were effective in |
| enhancing G80 measured in right
side audience when the source was aiming to |
| the left of the hall. The
top-aiming source caused very little difference |
| from the front-aiming
source. This can be attributed to the low ceiling in |
| the smaller hall and the low
proscenium arch as well as suspended ceiling in |
| the larger hall. |