※ 引述《Marsaliz (Starving Physicist)》之銘言：
: Now back to this question. A reed is driven by the air a player blows.
: The frequency depends on the driving force. When you are trying the high
: register, the way you blow triggers the higher mode of the reed. The 1st mode
: is not triggered. But the pipe still can pick up low-frequency sub-modes
: which happen to be the pipe's resonance.
: Again, it's my guessing. I always think the frequency of the vibraiton
: source is somehow also triggered by the pipe's resonances....
: CHCheng
Now we have another physicist, this is good. How are you
C-H?
There is a book by Fletcher, balled "the physics of music
instruments", that provide an answer with analytical calculations.
You can find one copy in your physics library. The physics
of trumpet is not too different from that of clarinet, and you may
write wome interesting articles on that, too.
The following is for engineers and scientists only:
After the "attack", the sound in a wind instrument is approximately
a steady state. Energy is suplied by the player and dissipated
into the environment, mostly from the bell (and tone holes for
woodwind), some from the brass or wood of the instrument. The dissipation
has peaks around the resonance frequencies of the bore for the
instrument under consideration, and those frequencies are small compare
to the reed's frequency if we are considering clarinet or saxophone.
For trumpet, trombone, etc, the effect of resonance frequencies is
important to the vibration of the lips.
The resonances of the pipe do not go up to the natural frequency of
the reed due to the presence of the tone holes. This is a character
of all woodwinds: there is a cut-off frequency above which the
sound from the pipe cannot be distinguish from the noise in the
environment.
I hope at least C-H, Jay, and Tony know what I am talking about.
Also I cannot guarantee they are all correct becasue I do not
have time to read enough about these.
Hsuan-Yi Chen
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