Oh my! We have done it again -- we were talking about the resonant
oscillation induced in a bridge by a nearly constant wind and now we are
arguing about the details of playing a bugle. Talk about wandering!
Let me refine my comment which started this side bar excursion:
Although I have spoken with several women who say that they prefer the
kisses of a trumpet player (for various reasons), I have no desire to play
an instrument which I have to stick in my mouth. But I do have friends who
do. From conversations with them It is clear to me that, in the case of
the brass instruments, the excitation produced by the flapping lips
controls the frequency of the note heard --- the loudness is controlled by
how near the flapping is to the resonant frequency of the instrument as
adjusted by the musician. (In a previous post I called this amplification,
Leigh doesn't like this usage, I don't much care what word is used, but it
seems clear that a trumpet is louder if the correct valve is pressed for
the note desired.) At least this is close enough for government work.
On the other hand, for the winds -- at least for most of them -- I ignore
the reed instruments as reed musicians have their own set of weirdnesses --
again I am not particularly expert here as the wind instruments require
insertion into the mouth, the pitch of the note played is governed almost
entirely by the configuration of the instrument -- not any driving excitation.
The example I gave previously was an organ pipe -- which is played by
applying a _constant_ stream of air. This is like the Tacoma Narrows
Bridge. -- where the general air flow was approximately _constant_ (some
like DC). Now the forces on the bridge may pulsate harmonically due to
Aeolian (Eudora says that this is the correct spelling this time) effects
of vortices etc. And if the resonant (I think that Leigh likes "normal" -
is it?) frequency is close to the Aeolian frequency (and the Q is high
enough), the bridge comes falling down, This is Leigh's original point,
with which I agree. And I agree that the TNB incident is not well used in
our instruction.
(Or if it is an Aeolian harp under consideration, it makes pretty sounds.)
This occurred in the case of the TNB when a collar, which connected some of
the support cables, slipped and abruptly changed the "resonant" frequency
of some of the oscillation modes to be closer to the Aeolian driving frequency.
And this is why some organ stops are called Aeolian.