fast air

Discussion in 'Trumpet Discussion' started by fels, Jul 18, 2008.

  1. rowuk

    rowuk Moderator Staff Member

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    Nordlands, you forgot something. With the lips pressed tightly together, we need pressure to open them, that energy is then LOST as applied to speed! They aren't open long enough for the air to pick up speed which would be the case if we just were blowing into free space. The trumpet fights back. That is why if you are not breathing right, your air backs up and you can't get rid of it fast enough when playing high! The simplified picture based on the garden hose/venturi just doesn't hold up. That is a direct current analogy that does not resemble our playing because too many pieces are missing.

    If you are up to comparisons, blow up a balloon then let go of it and calculate how long it takes until it is empty. Then blow it up again, stretch the nipple until it squeals. Calculate the time until the balloon is empty (it takes longer.........) That is because of the energy required to overcome the stretched but small "aperature". Our embouchure does not work by stretching, rather by compression and that also SLOWS the time needed to get rid of our air by a substantial amount (otherwise just like stretching the balloon). When we factor the backpressure of the horn at higher frequencies, there is a further SLOWING.


    The trumpet is an acoustic transformer - transforming higher pressure to lower pressure. All this venturi stuff does not apply to reactive systems. Pressure is not speed in a reactive system. The trumpet/mouthpiece/embouchure is not linear in the way air is dealt with. Most everything that is "common knowledge" in this respect is not true and has no basis in physics.
     
  2. nordlandstrompet

    nordlandstrompet Forte User

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    1 bar lung pressure - 4mm throat mpc
    2 bar lung pressure - 4mm throat mpc
    Take away the trumpet and put a balloon onto the mpc.
    Which balloon will be filled first?
    And why?

    Kinking a hose: Unless you give more pressure to the hose,
    the less water comes out, is correct.

    River: The water will of course try to raise on the narrow point,
    but before, in, and after this point the waterflow in litre per minute will be the same.
    In the narrow point the water speed through this actual point will be higher.
     
  3. kalijah

    kalijah New Friend

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    You are espousing faulty physics.

    The speed thru an aperture will depend on the pressure difference across that aperture. The size has no bearing.

    And it has nothing to do with the venturi effect. That has to do with the decrese of static pressure at higher flow velocity.

    Now, of course, the flows WILL be different.

    D Jones P.E.
     
  4. nordlandstrompet

    nordlandstrompet Forte User

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    If I squeeze the squealing balloon enough, I can get it to empty
    just as fast as the "open end type".
    But it needs to bear the pressure....

    Why do we back up air when playing high?

    As mentioned, the compression of the lips slows the time to get rid of
    the amount of "breathed in air". The higher notes, the more compression of the lips?
    So, with more compression of the lips, the smaller venturi, then faster air,
    but smaller amount of air getting through the lips/aperture?

    Small aperture, high speed air = high frequency?

    The fast air everybody talks about, is the air speed through the aperture,
    and NOT through the horn?[​IMG]
     
  5. kalijah

    kalijah New Friend

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    b15m wrote:
    Not exactly, the flow (and speed) will vary with pressure. It is not fixed flow due to fixed hole size.
     
  6. nordlandstrompet

    nordlandstrompet Forte User

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    The flow (and speed) will of course vary with different hole sizes?
     
  7. rowuk

    rowuk Moderator Staff Member

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    Nordlands,
    do a small experiment:
    sustain a loud low note
    now sustain a loud high note
    which note can you hold out longer and how much longer?

    Instead of filling the balloon without the trumpet, stretch it across the bell (or a harmon mute with stem) and fill it up playing a low note or high note. Here you will also have PROOF that the horn reacts much differently depending on frequency. Even if you could increase your available pressure for high notes, your analogy fails until the pressure is so high that the lips no longer vibrate. Then the mouthpiece throat wil be the deciding factor

    If your chops are reasonably together, you can sustain the high note MUCH longer than the low note. This should prove even to you that the quantity of flow is NOT linear, it goes DOWN as the pitch (pressure)goes up.

    Your mistake is the not applicable comparison. Our playing depends on our aperature opening AND closing at the frequency that we are playing. At higher frequencies, this becomes much less efficient because we INCREASE the mass of our lips by compressing them. It takes even MORE energy to blow them open - that is why your 1 bar behind the lips will NEVER make it to the throat of the mouthpiece except perhaps for pedal tones where the lips are flapping with minimal control - there is a lot of leakage then.

    A river and garden hose have no frequency dependent IMPEDANCE and no REACTANCE from the horn structure. The analogy is not applicable.

    Trying to reduce the physics of sound reproduction to constant flow analogies like garden hoses or rivers are where these misconceptions come from. They have no semblance to playing the trumpet.

    The truth is, I don't get higher notes by pushing harder. I get higher notes by training smarter. That means relaxing.

    If you use a lead trumpet player as an example, nothing changes. Their chops are stronger meaning that blowing harder just makes the high notes LOUDER. Their range is actually greater when they back off a bit and stop pushing as hard. That is because more of their air gets turned into sound as it does not "leak" through the aperature.
     
  8. kalijah

    kalijah New Friend

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    The flow will. The speed will not. Given that the pressure difference does not also change.
     
  9. kalijah

    kalijah New Friend

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    Simply put the smaller aperture,, in general. Will pulse air at a greater frequency. Frequency has nothing directly to do with air speed.

    However, greater air speed, and flow, may be required to sustain sound volume thru that smaller aperture. (due to horn acoustics) It depends on how loud you wish to play.
     
  10. nordlandstrompet

    nordlandstrompet Forte User

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    Does anybody actually READ what I am writing?

    I am writing about air speed through the aperture.
    NOT through the horn.

    Somehow, the air blown into a horn has to pass the aperture at some speed!
    Even if the lips opens/closes there will be an opening which lets the air come through![​IMG]

    A large aperture e.g. 3mm "dia", will let a large amount of air go through,
    but the relative speed of the air will be "slow" and the frequency of the lip motion
    will be "low".

    If the aperture is e.g. 2mm "dia" and you push the same amount of air through,
    the relative speed of air will be "faster" and the frequency of the lip motion
    will be "faster/higher".

    And yes! I can play all the slow relaxed 20-ish bars of the start of William Himes arrangement
    of Amazing Graze on 1 single breath on the flugel and even breath out afterwords
    without passing out!
     

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