the myth of "fast air"

Discussion in 'Trumpet Pedagogy' started by rowuk, May 2, 2008.

  1. tedh1951

    tedh1951 Utimate User

    7,799
    2,357
    Oct 18, 2007
    The Wide Brown Land
    Nordlandstrompet et al,

    We are getting a little theoretical here, but if we have slow air into a venturi - the air speeds up through the throat - and slows again through divergent duct of the backbore (other things happen and it would be prudent to assess them - but elsewhere). Think of it as trying to pass a fixed volume of air through a tube with a narrowing then widening bore - the volume CAN'T change so, as the diameter diminishes the air must speed up to get the 'fixed' volume through, as the diameter icreases the flow slows, but the VOLUME doesn't change. ROWUK's and NickD comments alude to the same thing. For reference see Bernoulli's Theorum.

    Another confusion that has been introduced with the gas turbine analogy is this, in gas turbines we, in general, manipulate the airflow to reduce airflow 'vibration' and in our trumpets we would rather have a little bit of controlled vibration - otherwise no sound. So, two different properties of air that are not really complimentary. The trumpet needs air column vibration but that doesn't mean large airflow - if we can get the "contents of the trumpet" to vibrate then that gives the sound - flow, it seems to me, has little to do with it.
     
    Last edited: May 11, 2008
  2. nordlandstrompet

    nordlandstrompet Forte User

    1,839
    221
    Apr 5, 2008
    Norway
    Thanks for dealing with us, your knowledge of the function of the gas turbine.

    This thread has given the fine members and guests of the forums, in addition to the discussion of "the myth", a lot of knowledge about car engines, waterhoses, guitar strings, ropes, jet engines, loudspeakers, different types of wood, etc etc.

    By the way; You are invited to a free lunch (as payment for your replies) if you some day should visit the southwest of Norway :D
     
  3. B15M

    B15M Forte User

    2,459
    29
    Dec 30, 2003
    Monroe Ct.
    What if we took a mouthpiece with the smallest hole possible and still play. Then we took the most powerful player in the world and had him or her play on it. Lets say the mouthpiece hole is so small that the player was always pushing the maximum amount of air through it.

    When the player moves the tongue to the roof of his mouth, does the pitch go up? We have already restricted the amount of air so why would the pitch change?
     
  4. nordlandstrompet

    nordlandstrompet Forte User

    1,839
    221
    Apr 5, 2008
    Norway
    I believe that the counter pressure in the mpc cup would make it very difficult to make the lips open/close (vibrate) if the mpc hole is smaller than the embouchure aperture. It would be like blowing air through a 10 inch concrete wall.

    About 15 years ago, the very fine cornetplayer/soloist/conductor/teacher, John Hudson (UK), visited my band to conduct the band at the Norwegian Nationals. He showed us that the tuningslide could be manipulated, by pulling the slide in, started the tone, and pulled the slide out and kept the tone at the same pitch until he had pulled the slide out of the cornet.

    By doing this, he showed that a strong embouchure itself had the ability to keep the notes in pitch. We had the possibility to control the pitch with a tuning meter. I believe he started the note with open valves pitch Bb with a strong "downbend" and ended with a strong "upbend". (15 years ago..) I can't remember if he mentioned the tongue position, but may be my memory is out of tune...

    veldkamp has earlier in this thread given us some good words about tongue position and use of "facemuscles"
     
  5. godchaser

    godchaser Banned

    778
    2
    Jun 17, 2007
    .

    Ah- much gratis there Ted. But i'm still unconvinced. :) No free lunch is sure so; i don't argue there's a fixed air volume. Although i feel like there'd be a cumulative increase in the players' energy or air pressure, by aid of a repetition of 'narrowing/widening' bore? Making for a more efficent use of the same volume, which would respond in the horn as greater volume, though not literally so. -You'd be getting a more intensified air-pressure, despite there being no increase of volume or energy from the player? The ratio of lost air-pressure, to gained, in the narrowing/widening bore progression would amount to a greater energy output at the bell than at the mouthpiece? Each time the air-volume cycles through the narrowing area it gatheres a little more pressure than it lost in the widening area? The volume of the air's changed character from point a to b, hasn't gained any speed, but just become a players' more effective energy?

    I dunno. :) -Particularly whether it'd amount to any appreciable benefit?


    Chris

    ___

    Nice post Smatt.

    .
     
    Last edited: May 11, 2008
  6. smatt401

    smatt401 New Friend

    12
    0
    May 11, 2008
    Wisconsin
    Questions regarding "fast air"

    Folks:

    I'm only a come-back player and a total non-starter in physics, acoustics, mechanics, etc. but I would like a few answers to questions re: "the myth of fast-air" in relationship to trumpet playing. I've never really understood the fast-air thing.

    Before asking the questions though, I'd like to make a brief detour to compliment everyone's use of the English language. Over my lifetime I have attempted to learn French, Greek, Hebrew, and Portuguese. Never in my wildest dreams would I attempt to discuss this topic in one of those languages. I'm impressed.

    Now my questions.

    First, is the following list of variables (setting aside the variables of the instrument & mouthpiece) comprehensive of those which must be investigated and/or be taken into account:

    Air volume
    Air pressure
    Air speed (i.e. "the myth")
    Shape of oral cavity
    Shape of aperture (oval vs. round)
    Condition of aperture (closed vs. open)
    Size of aperture
    Tension of aperture
    Depth of aperture (flatter vs. tube-like)

    Second, given the number of variables (whether or not the list above is comprehensive enough), would it not be possible to produce the same or, at the very least, similar results by adjusting different variables? Could, just for example, less aperture tension be compensated for by using a more tube-like aperture?

    Third, if increased air speed were all that is necessary to produce an upper register would this not be self-limiting? If I am understanding the super-fast air explanation correctly, it is necessary to arch the tongue to increase the air speed. However, in the early 60's when I first began playing, high C's were somewhat common among good professionals. Now I'm hearing about double or triple high C's and it doesn't seem reasonable that tongue arch alone has enabled this quantum leap in range.

    Next, as I envision the sound produced by a trumpet, I think of standing waves. Air pressure released in the oral cavity causes the lips to vibrate which produces a motion in the air molecules which motion travels to the bell. The bell opening resists the movement in the air molecules which causes a reflection back to the lips, forcing them closed. Continued air pressure from the oral cavity overcomes the resistance and the motion in the air molecules travels back to the bell opening, which again resists the motion in the air molecules, reflecting the motion back to the lips in/on the mouthpiece.

    All this happens at the speed of sound, 343 m/s, and creates a standing wave(s) with node(s) within the tubing. At some point, the motion in the air molecules overcomes the resistance of the air molecules at the bell and sound "escapes." (I believe something like 85-95% of the "sound energy" is retained in the tubing).

    (However, it also seems reasonable to me that the standing wave reflected back to the lips also affects, not only the air within the oral cavity, but also in the sinuses and the pulmonary cavity (given an open throat). That is, there is a sound source (the lips), a sound director or "amplifier" (the instrument), and additional resonance chambers (sinuses, oral cavity, pulmonary cavity). This could affect tone quality but not pitch. Which leads to the interesting observation that playing a brass instrument is the most voice-like since it is the only instrument which uses so much of the human body both to produce and to color sound).

    Hence, it is my understanding that it is not the air moving through the instrument which produces sound but rather the excitation of air molecules which then pass their motion on to other molecules. This is somewhat analogous to the well-understood motion of wave-action in a body of water.

    Therefore, the speed of the air (which naturally implies motion), cannot be the controlling factor which enables higher pitches to be played. Is this assessment generally correct?

    Finally, how can I, as an aging comeback player, develop my range to C above the staff? I'll never be a Maynard or a Cat but I sure would like to be able to play a rich and lush C.

    smatt401
     
    Last edited: May 11, 2008
  7. nordlandstrompet

    nordlandstrompet Forte User

    1,839
    221
    Apr 5, 2008
    Norway
    Smatt401

    You are asking very good questions, but it seems that this thread just died without an official conclusion.

    I believe that the "Mythbusters" would have concluded the myth as "Plausible"

    The thread has moved to the 2. stage, and is now called: "Effiency in stead of fast air"
     
  8. tedh1951

    tedh1951 Utimate User

    7,799
    2,357
    Oct 18, 2007
    The Wide Brown Land
    Chris,

    Air passing through a fixed volume system, like the one we are discussing consists of two air pressures - dynamic pressure - think of flow as dynamic pressure - and static pressure, the pressure that (in effect) acts at right angles to dynamic pressure (not strictly true, but close enough for illustration). The sum of these two pressures will always be constant so that as dynamic pressure increases (increase in flow), static pressure must decrease. All is in balance - regardless of the number of convergent-divergent-convergent, or divergent-convergent-divergent elements that are included in the system, you can't get any overall change across that system. It is simply not possible.

    We are however, vibrating a fixed column of air - think of the trumpet being filled with air and we are vibrating that air - so this is our output, vibration. This transfers to the ambient air and we hear it as (hopefully) a full throated beautiful fff Double C, or a controlled and delicate p @ low F# depending on how the trumpeter creates the initial column of air, and the initial vibration. So all we can change is the frequency by vibrating the lips at a different rate, but once again, this is not the full story because it can only describe an INSTANT in time, but it is reasonably close. Have a look at NickD's website and see how slowly he inflates the soap bubble with his trumpet - not a lot of flow there - but plenty of capacity to vary the sound levels and pitch. I hope this helps.
     
    Last edited: May 12, 2008
  9. godchaser

    godchaser Banned

    778
    2
    Jun 17, 2007
    .


    No doubt your right Ted, your good to indulge my ignorance. And we gotta dance with who we brung, but that's not a life sentence :) -given the timing you spoke to there? Which you gathered was my meaning of (intensifying) air pressure, or effectively creating something from nothing. If the dynamic pressure can be moved through, or around the static pressure in such a way that it offers less resistance in negotiating its mirrored dependence -then that's a good trick. Its balance of equal sum's forever intact, but pliable to a seemingly imbalanced net effect nonetheless. This, understanding that 'you can't get an overall change in the system'. See you in the 'efficency' thread. And likely you've already thunk up some ways to do that?

    I'd tell you, if i had. :)

    Possibly a pipe design with 'widened' bore shaped like a bubble, connect of narrow bore shaped like a cone's, doable? The bubble harbors a static pressure more readily than dynamic, creating a tricked up sound?

    -
     
  10. rowuk

    rowuk Moderator Staff Member

    Age:
    61
    16,613
    7,957
    Jun 18, 2006
    Germany
    The mouthpiece trick has nothing to do with the playing experience unless we buzz into both sides.................... It is the wrong visualization.

    We need to get the "DC" (direct current) component (simply blowing air) back to its minimal role. The buzzed (AC or alternating current) component is what counts when we are making music. Like I said, the "airflow" part is only tuned to let us breathe at regular intervals. A super efficient mpc/horn COULD use so little air, that we essentially suffocate! An inefficient "free blowing" horn/mpc could pass air so quickly that we can't phrase more than a couple bars. Good designers come up with a functional comprimise.
     

Share This Page