The demo in the video here shows sound can be made with a membrane without pushing air through but at no point does it match the tone of a normally played horn.
Obviously this set-up is acoustically inferior to a normal and complete instrument as some of the acoustic energy of is lost through the vent. The membrane also likely limits how much can be transmitted.
Notice the "vent" that allows air to flow out of the side of the mouthpiece cup must have some flow resistance. This allows the air pressure to rise on the air pulsation sufficient to play a tone. The pressure in the cup rises and deflects the membrane at a high enough velocity to create a pressure wave on the downstream side, which then transmits through the instrument.
Joined: 30 Aug 2017 Posts: 683 Location: Texas South Plains
Posted: Wed Aug 03, 2022 4:39 pm Post subject:
C'mon man! 1,628 papers. One a week for 30 years? Seriously?
Maybe a comic strip, but physics? No offense, I hope. I am just trying to do the math! _________________ huntman10
Collector/Player of Fine (and not so fine) Brass Instruments including
Various Strads, Yammies, Al Hirt Courtois, Schilkes,
Selmer 25, Getzen Eternas, Kanstuls (920 Pic, CG)
Martin Custom Large Bore, Lots Olds!, Conns, etc.
Has anyone come up with a demonstration using maybe electronically actuated "lips" that more closely simulate the actions of human lips?
The demo in the video here shows sound can be made with a membrane without pushing air through but at no point does it match the tone of a normally played horn.
What would be the point of your demonstration, exactly? That the trumpet could be played like a trumpet? I'm not trying to be cheeky, genuinely don't understand.
I.e. mechanical "lips" where the buzzing is actuated electronically not by having air blown through them. This membrane demo shows an approximation of a trumpet sound but doesn't show that the sound can be the same without air flow.
Billy B wrote:
Listen at 6:20 in the video.
Meh - same as my reply above, still not the same. _________________ Getzen Eterna Severinsen
King Silver Flair
Besson 1000
Bundy
Chinese C
Getzen Eterna Bb/A piccolo
Chinese Rotary Bb/A piccolo
Joined: 24 Dec 2018 Posts: 3298 Location: Endwell NY USA
Posted: Fri Aug 05, 2022 5:13 am Post subject:
Robert P wrote:
I.e. mechanical "lips" where the buzzing is actuated electronically not by having air blown through them. ...
--------------------------
If by 'mechanical lips' you mean moving surfaces that open and close, but do not 'pump air', then there wouldn't be much (if any) sound produced because the air pressure inside the tubing would not be changing.
Using a membrane transducer (or small speaker) will 'pump air' and produce the pressure changes that are needed. _________________ Most Important Note ? - the next one !
KNOW (see) what the next note is BEFORE you have to play it.
PLAY the next note 'on time' and 'in rhythm'.
Oh ya, watch the conductor - they set what is 'on time'.
Using a membrane transducer (or small speaker) will 'pump air' and produce the pressure changes that are needed.
To have a speaker that could do equivalent sound levels of tone would require as significant power amplifier.
One issue with most speaker setups at that size feeding pure sine waves: The self-resonance of the speaker appears to affect the complete system response. This gives a broad "bump" around the Helmholtz resonance of the mp cup and even higher.
I.e. mechanical "lips" where the buzzing is actuated electronically not by having air blown through them. ...
--------------------------
If by 'mechanical lips' you mean moving surfaces that open and close, but do not 'pump air', then there wouldn't be much (if any) sound produced because the air pressure inside the tubing would not be changing.
Using a membrane transducer (or small speaker) will 'pump air' and produce the pressure changes that are needed.
By mechanical lips I mean artificial lips that do the same thing human lips do but without air flowing through them. If it's true that the lips serve only to create the buzz and set up a wave in the existing air within the instrument, that no airflow is needed then they should work. _________________ Getzen Eterna Severinsen
King Silver Flair
Besson 1000
Bundy
Chinese C
Getzen Eterna Bb/A piccolo
Chinese Rotary Bb/A piccolo
Chinese Flugel
Last edited by Robert P on Fri Aug 05, 2022 5:49 pm; edited 2 times in total
Joined: 08 Jun 2017 Posts: 61 Location: Toledo Ohio
Posted: Fri Aug 05, 2022 12:31 pm Post subject:
Re: Tom LeCompte
Apparently, he is the physics coordinator at CERN working on coordinating the large Hadron Collider science projects. He would get credit for papers he advised or helped with (I believe).
Been musing on this one (and thanks for the many interesting opinions) and this question occurred to me:
- if the purpose of the lip vibration is to energize standing waves in the horn; and
- if the only real reason air passes through the horn is because that's the only way we have of exciting the waves; and
- the loudness of the horn is directly related to the amplitude of the energy being input by the player; and
- the output frequency is dependent upon the frequency of the vibration produced by the player...
...then why & how do mouthpiece variations (ie. cup size, shape, etc.) influence the harmonic content of the wave? Is an energized standing wave not an energized standing wave? Are timbral variations in the waves being created by different mouthpieces? If so, how?
By mechanical lips I mean artificial lips that do the same thing human lips do but without air flowing through them. If it's true that the lips serve only to create the buzz and set up a wave in the existing air within the instrument, that no airflow is needed then they should work.
. . . but then I read on another website that the robot has an artificial lung, so it must be pushing air through its artificial lips. _________________ "He that plays the King shall be welcome . . . " (Hamlet Act II, Scene 2, Line 1416)
"He had no concept of the instrument. He was blowing into it." -- Virgil Starkwell's cello teacher in "Take the Money and Run"
Joined: 24 Dec 2018 Posts: 3298 Location: Endwell NY USA
Posted: Fri Sep 02, 2022 7:04 am Post subject:
Proteus wrote:
...
...then why & how do mouthpiece variations (ie. cup size, shape, etc.) influence the harmonic content of the wave? Is an energized standing wave not an energized standing wave? Are timbral variations in the waves being created by different mouthpieces? If so, how?
Just curious...
-----------------------------------
The 'standing wave' has a very complicated shape - it's not a simple nice and even sine wave. The wave has various 'internal' amplitude variations that provide the 'harmonic content'; those variations come from the mouthpiece configuration, the player, and the horn itself.
I think that a lot of the content of the wave comes from irregularities in the shape of the air pressure curve during lip vibration / pulsation, along the duration of an entire wave cycle. _________________ Most Important Note ? - the next one !
KNOW (see) what the next note is BEFORE you have to play it.
PLAY the next note 'on time' and 'in rhythm'.
Oh ya, watch the conductor - they set what is 'on time'.
Joined: 22 Oct 2008 Posts: 2412 Location: Maryland
Posted: Fri Sep 02, 2022 7:42 am Post subject:
john4860 wrote:
Re: Tom LeCompte
Apparently, he is the physics coordinator at CERN working on coordinating the large Hadron Collider science projects. He would get credit for papers he advised or helped with (I believe).
Pretty impressive stuff.
John
Agreed. Very impressive. (And overall, a very interesting thread here, with lots of good replies.) We live in a world where anyone online can come across as an "expert". But once in a while, that person posting something actually is one.
Mike _________________ Bach Stradivarius 43* Trumpet (1974), Bach 6C Mouthpiece.
Bach Stradivarius 184 Cornet (1988), Yamaha 13E4 Mouthpiece
Olds L-12 Flugelhorn (1969), Yamaha 13F4 Mouthpiece.
Plus a few other Bach, Getzen, Olds, Carol, HN White, and Besson horns.
We live in a world where anyone online can come across as an "expert". But once in a while, that person posting something actually is one. Mike
I chuckled when I read this, because it is so very true! (How's that for adding two very much unnecessary adjectives?)
A corollary is that on TH, sometimes an expert in one thing, like playing the trumpet, acts like an expert in another thing, like acoustics. _________________ Craig Mitchell
The technical system of playing does not require a knowledge of quantum physics to understand. The brass world is a bubble and an echo chamber that only entertains explaining EVERYTHING in terms of "compression" or "air-speed", neither rarely understood or even defined. Often just repeated hearsay of the popular language among players and teachers.
Quote:
- if the purpose of the lip vibration is to energize standing waves in the horn; and
The lips themselves do not energize the standing wave, the pressurized air volume on each pulse of air from the opening aperture does.
Air pressure= energy density
Air pressure x air volume = energy
Quote:
- if the only real reason air passes through the horn is because that's the only way we have of exciting the waves; and
There is a net flow but the air volume per pulse that I mentioned before is related to volume per pulse x frequency
or, volume x 1/T = volume/Time
which is FLOW.
Quote:
- the loudness of the horn is directly related to the amplitude of the energy being input by the player; and
loudness is air power input by the player x efficiency
which is, power in = air pressure x air flow
sound power out = air power in x efficiency
Quote:
- the output frequency is dependent upon the frequency of the vibration produced by the player...
For the fundamental frequency of the tone played yes. But the standing wave is not a sine wave. Since it is non-sinusoidal it has harmonic content. (Not to be confused with the harmonic series of the instrument resonance)
Quote:
...then why & how do mouthpiece variations (ie. cup size, shape, etc.) influence the harmonic content of the wave?
Everything about an instrument affects it's acoustics, that of course includes the mouthpiece.
Quote:
Is an energized standing wave not an energized standing wave? Are timbral variations in the waves being created by different mouthpieces? If so, how?
The short answer is, a smaller mouthpiece more drastically increases the nonlinear impedance of the instrument. Obviously a propagating pulse into the mouthpiece cup will "pressurize" that smaller air volume in the small cup in a shorter duration than a larger cup. So, as more air power is applied, the more non-sinusoidal the pulses become. The high harmonics are dominantly transmitted out of the bell. They do not "resonate", only the fundamental contributes to the "standing" wave.
(If anyone attempts to explain mouthpiece or instruments acoustics in terms of "air speed" you can be confident that they don't understand what they are explaining.)
Joined: 23 Mar 2003 Posts: 9003 Location: Hawai`i - Texas
Posted: Fri Sep 02, 2022 10:38 am Post subject:
Not brain dead, but what does this all mean? How does it apply to me as a trumpet player beyond putting the horn to my lips and blowing? _________________ "If you don't live it, it won't come out of your horn." Bird
Not brain dead, but what does this all mean? How does it apply to me as a trumpet player beyond putting the horn to my lips and blowing?
Exactly. I usually avoid any thread that invokes the word "physics" because I never see any practical application for playing the trumpet -- just debate and formulas. How do we take all of this and make better trumpet players? _________________ --Matt--
No representation is made that the quality of this post is greater than the quality of that of any other poster. Oh, and get a teacher!
Joined: 24 Dec 2018 Posts: 3298 Location: Endwell NY USA
Posted: Fri Sep 02, 2022 11:16 am Post subject:
kehaulani wrote:
Not brain dead, but what does this all mean? How does it apply to me as a trumpet player beyond putting the horn to my lips and blowing?
-----------------------------------------
The value in having knowledge is that it enhances your 'language translator'. That can be useful to understand the important parts of what is 'done' versus what is 'said or written'. _________________ Most Important Note ? - the next one !
KNOW (see) what the next note is BEFORE you have to play it.
PLAY the next note 'on time' and 'in rhythm'.
Oh ya, watch the conductor - they set what is 'on time'.
All times are GMT - 8 Hours Goto page Previous1, 2, 3Next
Page 2 of 3
You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum
