竹片(1):
______ 相信我,左圖畫的是竹片.
/######\
L /## ##\ R 對於豎笛(薩克斯風也是一樣)竹片的重要性自不待言.
|# #| 所以在這裡我很努力的擺了張漂亮的圖片以便說明下面要
| | 討論的主題.
| |
| HH | 圖中 ### 的部分就是所謂竹片的"頂端".而看起來像
| HH | 有張微笑的嘴型的部分就是"根部"了.至於標記上H的部分
| HHHH | 則是竹片的"心部"啦.
| HHHH |
| HHHH | 當我們吹豎笛時,發出聲音是因為竹片的振動造成的,
|\ HHHH /| 而不是來自我們肺部的空氣的振動造成的.你也許可以用
| \____/ | 某種特別的機器使竹片快速的振動(當然如果你是超人的
|--------| 話,當然也可以用手指就辦到),就會發現這樣也可以不須
| | 將空氣吹入豎笛中就使它發出某些音.
| |
| |
| | 當我們吹豎笛時,竹片是以非常複雜的模式在振動著.
| | 小鼓的振動模式已經是夠複雜了的,但如果看過竹片振動
| | 時的形狀的話,就會很容易明白為什麼模擬竹片的振動要
較諸更麻煩許多.
以下就是關於竹片振動時定性的敘述:
(譯註:或說是"邊界條件-Boundary Conditions"吧)
比較理想的近似方式可以看成當竹片振動時,竹片的"根部"是固定而不振動的,而
竹片的"頂端"則是振動的部分.
在演奏低音域時的音時,竹片的頂端是完全的振動著,也就是說,你可以想像竹片
的根部是固定的,而其餘的部分則是以均勻的振幅由左至右的振動的.
(譯註:所謂的"均勻"應該是指根部的振幅最小是零,一直到頂端的振幅最大)
到了高音域時,竹片的振動卻是以"左-右-左-右-左-右..."的模式振動著.也就是
說當竹片的左端是向上擺動時,右端卻是向下的.反之亦然.
因此 ### 的部分(也就是頂端)較薄的竹片可以看作是較好的竹片,因為這樣在高
音時會比較容易振動.而 HHH 的部分卻應該厚一些,因為我們不希望在演奏低音域時
會因為太薄而發出很多的雜音.
Bonade博士甚至說他更喜歡左右不平衡的竹片,因為一般人慣用右手來處理竹片,
所以竹片的左邊應該比較厚一些,因為嘴會咬這邊更用力點.我真的不信這樣的說法,
因為人的嘴型彼此不太相同.但至少他的分析可以說明一點:在討論人身體的特性時,
是絕對沒有左右對稱這回事的.
下一篇我將試著把其他對於單簧片振動的實驗作個總結,也許會用"手動振動"的
論點再作些解釋
陳宣毅
譯:Tony Hunag
Reed: (I).
______ That's a reed, if you believe me.
/######\
L /## ##\ R The importance of a reed for clarinet (and
|# #| (saxophone) is obvious. So I put a beautiful
| | figure for the object under discussion here.
| |
| HH | The ### part is called the "tip". The part which
| HH | looks like a smiling lip is the "root", the part
| HHHH | marked with "H" is the "heart".
| HHHH |
| HHHH | When we play a clarinet, it is the vibration of
|\ HHHH /| the reed which produce the sound, not the air
| \____/ | which goes out from our lung. You can vibrate a
|--------| reed fast by some machine (or your finger, if you
| | are a superman) and produce some sound from the
| | clarinet without blowing any air into it.
| |
| | When we play a clarinet, the reed is vibrating
| | with very complex pattern. The vibration of a
| | circular drumhead is complex enough, but, if you
look at the shape of a reed, it is easy to
understand that a calculation of the vibration
of a reed is much worse than that.
A qualitative description of the vibration of the reed is the
following:
The root of the reed is, to a good approximation, fixed and not
vibrating. The tip is the part that is vibrating.
At low register, the tip of the reed is vibrating as a whole, i.e.,
you can imagine the root being fixed and the rest is vibrating with
a uniform amplitude from left to right.
At high register, the tip of the reed is vibrating with L-R-L-R-....
pattern, i.e., when the L-side of the tip is up, the R-side of the tip
is down, vise versa.
As a result, a reed with thinner "#" part is considered as "good"
because it is easier to vibrate in high register. Also the heart has to
be thick because you don't want a lot of noise from the reed when you
play the low register.
D. Bonade said that he likes unbalanced reeds better. Because we use
the right hand to handle the clarinet, hence, the left side of the reed
should be harder because we bite more on that side. I don't really
believe it, though, for the shapes of our mouths really differ from one
another. But his observation told us the left-right symmetry is
nonexistence when talking about human body.
Next time I will try to summarize some other experimemtal results on
the single reed and perhaps use hand-waving argument to explain them a
little bit.
Hsuan-Yi Chen
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