Nordlands wrote:
Quote:
Mr. Jones
I have been a part of this discussion, and posted a couple of ideas about how the air passes through the horn. My conclusion has been that the air flows at different speeds through the lips, mouthpiece, tubes and belltube.
The idea I have tried to explain, has been that the air flows with the same amount through the whole instrument, but changes to higher/fast speed when passing narrow points at its way. There is an attachment in one of my earlier posts which is trying to clarify what I am trying to explain. Do you have any idea if this "venturi suggestion" is a good explanation?
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Yes, the air flow is constant through the system, from lungs to bell. (With a minor exception)
And the speed can be determined anywhere by considering the cross section.
But you must be careful that you understand that because the air is "faster" through a narrow segment, this does not mean that the air has more energy due to this increase in speed due to "narrowing".
And it also becomes evident that the greatest velocity is through the aperture.
Also, increasing the narrowing anywhere in the system before the mp cup also increases the resistance and would yield a smaller flow for the same pressure. But usually not much less for most normal actions of tongue arch.
For example, tongue arch proponents make the claim that arching the tongue "speeds up" the air and the resulting "faster" air yields a higher pitch.
There are two faults to this way of thinking:
1. Arching the tongue will never increase the air energy at the aperture (total pressure) above what the lungs provide. and..
2. The pitch will not change unless the aperture pulsation frequency changes. The aperture itself must change. Namely, become smaller, to ascend.