How much of the resonance comes from the bell?

[BrianJohnston]

As many of us know, the bell truly is the majority of the resonator for the instrument, i'm wondering if anyone knows any info on how much of the bell resonates vs the rest of the instrument (Tuning slide, valve section, hand slide) Ball park percentage guesses...

[Dennis]

It wouldn't be too difficult to measure this with modern tools.

Get the spectra of a free buzz, a buzz with mouthpiece on a slide extended to the length necessary for Bb2 fundamental, and the full horn.

The slide approximates a cylindrical tube. You could improve it with a length of 0.500 ID copper pipe of the appropriate length.

From the spectrum, assess the bandwidth of the buzz on the cylinder vs. the bandwidth of the fundamental of the assembled instrument.

As a WAG (not even a scientific WAG), I'll guess that the bandwidth of the assembled horn around the fundamental pitch is 95% narrower than the cylinder. (That guess is based on hearing Dennis Brain do the Rondo of a L. Mozart horn Cconcerto on a length of hose vs. Brain's playing of Strauss and A. Mozart horn concerti on his Alexander Bb. You can hear the pitch, but it's very fuzzy. Also, Brain cheated and used a funnel as a primitive bell in his hose.)

I'm also going to guess that this varies quite a bit from partial to partial.

[harrisonreed]

The free buzz measurement would be not relevant to the measurement of the instrument.

[boneagain]

As many of us know, the bell truly is the majority of the resonator for the instrument, i'm wondering if anyone knows any info on how much of the bell resonates vs the rest of the instrument (Tuning slide, valve section, hand slide) Ball park percentage guesses...

I certainly don't know this. As Robcat noted in his "vibrato" thread, stringed instrument bodies resonate significantly and are largely responsible for the sound that gets out into the room.

Richard Smith did some interesting study on longitudinal vibration on brasswinds.

But overall I think you'll find that ANY resonance of the bell is pretty trivial relative to the direct air column standing wave interface to the room out the bell. My horn has a distinct ringing that I can excite by playing a moderate volume around E (lucky for me it does not match ANY E in any group I've played with.) Other players cannot hear that ringing from 10 feet away.

If I play loudly enough I can feel vibrations in the metal at different points along the horn.

Thinking about it, that is energy transferring from the standing wave inside the horn. To me that suggests that rather than all this vibration adding to the colors of the horn, it subtracts. I suppose I could test that by recording a series of E notes around, then including, the one that rings. I'd need to hold the pitches very steady, AND match the volumes within a dB or, likely, even closer. Probably a job for a much younger, in-shape player With sufficient volume and pitch matching one could compare the FFT profiles of the different notes and see if the ringing E adds energy to the recorded note, or subtracts it.

Regarding comparing a straight tube to a bell shape: not sure that will address resonance of the bell. I'm certain it won't in the "vibrating cello body" sense. The straight tube will yield every other partial. The combination of bell and cup squash the straight tube partials to approximate a "natural" harmonic series.

So, I guess I have a question: does your question relate to the vibration of the material as in the string instrument sense, or the vibration of the air column?

BTW: I am working on starting a thread on using Audacity, tunable, and Python to make usable but certainly not perfect comparisons like the ones mentioned by Dennis and I. I have a method and code, but need to strip down the wording. Running on and on takes no time at all... editing to be kind to readers takes a lot longer

[BGuttman]

I have a "fake butt" (a Holton Collegiate with the bell flare sawed off to simulate a Sackbutt). I found that the intensity of sound is reduced by at least half. I never used the thing in an early music ensemble, but I did use it in a High School musical pit band (with un-miked singers). I was able to keep the sound level below the singers more easily. Feedback to me was pretty good, supporting Boneagain's theory that the whole instrument creates feedback. I never subjected the thing to any acoustic analysis, and unfortunately I now can't.

[elmsandr]

So, I have some thought here, and some observations from a pretty particular hang with some interesting instruments this weekend.

First, the engineering thoughts. If you have a measurable response, with different, defined input scenarios you can classify and sort things into main effects and interactions. Read up on Design of Experiments and do one of the paper airplane or paper helicopter experiments to see how the math works. It is fun and involves just a little multiplication and addition, nothing too complicated. In trombone terms, interactions can often be seen in some of the common combos out there; heavy slide/light bell, or maybe nickel slide/red bell. So, the question you ask, I read it as ‘what is the main effect on resonance due to the bell?’ I’d have a hard time to quantify that, though I would argue it is far larger for the player than the audience. I’ve become more convinced over the years that the only real difference to the audience is how the horn changes what the player wants or is able to do… but that may be a bit controversial so let’s ignore that for a bit. Relative to the other pieces on the horn, I’d say the bell can have a fairly large effect…. But the overall effects of the minor horn construction differences are dwarfed by shape of wind column and the player. Hard to make drastic changes in those last two, so that’s where we play around.


Some observations from an incredible equipment geek hang with a fellow forum-ite this weekend. I’ll let him identify himself if he chooses, but y’all may guess just based on the horns I discuss. We had a pretty amazing set of horns between his and mine:
(3) Bach 45s, each from a different factory
(3) Bach 50s, each again from a different factory
Some pretty rare and interesting 42 bits to add in for good measure.
Slides to fit in varieties of bores 547 through 578 with I think every tripe of dual bore available. Materials from yellow to rose to some nickel… makes from Bach, Shires, an Edwards, and some customs from private maker and M&W…

This was something pretty unique for me, as I cannot recall going though something quite like this where the components were all so similar, but still with such a broad variation of composition and materials… entirely different than something like Edwards or Shires fittings… not everything was able to be fully swapped to pinpoint some individual components.

So, not a DOE, so no way to mathematically separate out the results, even if we were trying to do that… but we weren’t. But a thing that struck me on these combos more than I have ever fully noticed… the interactions were so very strong on some of the “less standard” slides. With a pair of the slides (an all rose 42 and a Bach like shires).. there were some very clear matches on bell sections with slides. Not that the others didn’t work or wouldn’t maybe even be better for some scenarios…. But a few of these combos could be described as ‘magic’. The interactions were so much stronger than the main effects of the slides on the individual bells… I didn’t really know what to do with the information.

The features that drew my attention yesterday… articulations, ‘broadness’ of sound, sweetness, and overall resonance… there were distinct differences to me as a player, a little less when listening, but mostly striking obvious differences in the small-ish living and dining room where we were playing. I had a pretty decent feeling that a handful of these combos may respond quite differently in a large hall. Would it sound different? Or would it just inspire a different level of input from the player? Is there any way I could measure these honestly to try to rate the differences? I doubt most of them would show up in any recording setup (at least not with my terrible playing), but they felt so different, they would lead me to changing things in how I approached them.

Anyway, I’ll stop rambling for a bit and say “it depends.”

Cheers,
Andy

[robcat2075]

I think many mistaken ideas about what the trombone bell does arise because of its resemblance to the woofer and tweeter cones of an audio speaker and its similarity in name to actual ringing bells.

[freeman]

https://studioclass.substack.com/p/tone-part-2

OP: good to meet you this weekend

[LeTromboniste]

I'm not sure I understand the premise of your question.

The resonator is the whole system, and it's what allows there being a standing wave. The bell is not what allows that resonance to happen (I.e. a straight pipe is also a resonator), not at all, so saying the bell is "truly the majority of the resonator" makes no sense.

In terms of its effect on resonance, what the bell does, is it changes the spacing of the partials, compressing them, because standing waves with high frequency/short wavelengths follow the curvature further and effectively "see" a longer pipe, and are therefore flatter. So if anything, the bell is where the least resonance happens, because as you get further out into the flare, fewer and fewer frequencies actually resonate in that space.

The bell, however, is the radiator of the instrument, the interface that allows the standing wave inside the instrument to make the air outside of it vibrate. A straight pipe has a very small and inefficient interface. A sackbut or hackbut has the "bell effect" with regards to the resonance, but the lack of flare means the interface is still somewhat small and the bell is still not a super efficient radiator, so the sound is softer. A big modern flare is a very efficient radiator. The efficiency is not the same across all frequencies though, so the shape and size of the bell affect timbre.

The bell is also the part of the instrument that is most free to mechanically vibrate, and that will also affect the tone, but not by adding to the sound, rather by subtracting.

[2bobone]

During the performance of a piece of Richard Wagner by the NSO, there was indicated in the score an offstage "Steirhorn" [Sp?] part. The conductor, Antal Dorati, interpreted it to be the horn of a steer, similar to the "Shofar" used in Jewish ritual. To produce the effect we used my "Coffey Model" Conn 70H that had not one, but three screw bells. The horn was played without any bell attached and satisfied Dorati's requirements perfectly despite the obvious difference in the length of the two instruments. Now that screw bells are more of a mainstream feature, it can be easily demonstrated that the bell is a crucial part of the resonance of any trombone. As to the Wagner piece, I'll leave it up to the musicologists out there to figure out what it was !

[LeTromboniste]

During the performance of a piece of Richard Wagner by the NSO, there was indicated in the score an offstage "Steirhorn" [Sp?] part. The conductor, Antal Dorati, interpreted it to be the horn of a steer, similar to the "Shofar" used in Jewish ritual. To produce the effect we used my "Coffey Model" Conn 70H that had not one, but three screw bells. The horn was played without any bell attached and satisfied Dorati's requirements perfectly despite the obvious difference in the length of the two instruments. Now that screw bells are more of a mainstream feature, it can be easily demonstrated that the bell is a crucial part of the resonance of any trombone. As to the Wagner piece, I'll leave it up to the musicologists out there to figure out what it was !

It's just a medieval hunting horn, literally a hollowed out steer's horn, with a mouthpiece carved into or attached to the small end. I played that Wagner part too, in Lorin Maazel's arrangement where he specifies the notes to be played (not sure how it is in the original). We used bell sections with the mouthpiece taped into the slide receiver. IIRC we got the right notes with one bell played straight and one bell with the valve engaged and the tuning slide pulled out a lot.

But I have to differ. The bell is of course a crucial part of defining the way the sound projects to the listener, and the tone of the instrument, but it's not what makes the instrument a resonator.

[timothy42b]

I certainly don't know this. As Robcat noted in his "vibrato" thread, stringed instrument bodies resonate significantly and are largely responsible for the sound that gets out into the room.

Richard Smith did some interesting study on longitudinal vibration on brasswinds.

But overall I think you'll find that ANY resonance of the bell is pretty trivial relative to the direct air column standing wave interface to the room out the bell.

Agree.

The bell is important only because it surrounds the air column and confines it to a particular shape.

The air column vibrates, with the length of it determined by where the sound wave reflects. Reflection occurs at any impedance mismatch, and impedance mismatches are always frequency dependent, so the length of the horn is effectively different at different pitches. The bell shape accounts for that.

But the bell vibration? Nah. Tap it with your finger. You just put more force into it than the air pressure of the sound wave.

Stringed instruments are different. The instrument body is between the string and the air, serving as a filter. So it's vibration modes should directly affect the sound.

[elmsandr]

So, we’ve drifted into the physics portion here a bit… fun, but not what the OP intended, probably.

If you can make a note on the horn, the physics question is answered… it is resonant and a standing wave (note) was produced.

Musically, aesthetically, that isn’t what we generally mean. Hold two horns of the same make and blow them.. one feels more resonant… one wants to speak easier and cleaner, faster articulations and seems to have a more vibrant sound… I don’t think there’s a great way to quantify that. I don’t think my playing is consistent enough to measure it in any repeatable or reproduceable manner. From above, I still believe it has more to do with the feedback to the player and thus altering the input than any actual effect on the output, but that is my admittedly 1/2 arsed theory.

Interestingly, I spent some time with some calipers on those horns yesterday… of the 45s, one of the flares is a different shape. After a certain point, it is about 0.010” larger for about 12”, then the throat starts to open up a little earlier to be larger sooner before ending at the same diameter and the same linear length. This, to me, could explain a lot of the differences there. The various other components that are supposed to be just cylindrical tubing? I got nothing there. They had few, if any measurable dimensional differences but definitely felt different to play.

Would love to have a way to prove it,
Andy

[2bobone]

In an earlier post I mentioned a "Coffey Model" Conn 70H that I once owned that had three screw bells. To the best of my recollection there were an 8" bell, an 8 1/2" bell and a 9 1/2" bell. They sounded remarkably different one to the other even though they seemed to be made of the same material. If we are all talking about resonance as the complexity of color and overtones that we hear as we play, I definitely think that the size of bell has a huge effect on the color [or in my definition, the resonance] of any instrument. Are we all on the same page or am I just confused as usual ?

[BrianJohnston]

https://studioclass.substack.com/p/tone-part-2

OP: good to meet you this weekend

Nice to meet and play with you as well, & thank you for the video

[BrianJohnston]

Replying to LeTromboniste: I guess I meant "Vibrate" not resonate. To most professional brass players, the words resonate, radiate, & vibrate mean the same thing. I suppose I will try again with my question, can we try to keep the answers simple please? This seems to have become a much more complicated rabbit hole than I originally intended it to become.

How much would the original sound of a horn be changed if someone only changes the valve section, vs changing the valve & the slide vs changing the entire horn?

[harrisonreed]

Replying to LeTromboniste: I guess I meant "Vibrate" not resonate. To most professional brass players, the words resonate, radiate, & vibrate mean the same thing. I suppose I will try again with my question, can we try to keep the answers simple please? This seems to have become a much more complicated rabbit hole than I originally intended it to become.

How much would the original sound of a horn be changed if someone only changes the valve section, vs changing the valve & the slide vs changing the entire horn?

If you look around this forum and others, and talk to professional brass players, at least in my experience, these words in bold mean very different things to different pros. I disagree with this statement in bold.

I think your original premise/question is not so simple, and definitely not something we can be objective about. You're also going into it biased -- "we can all agree that the bell is truly the majority of [something this thread had shown that words don't describe objectively]" -- So the answers will be all over the place, and you've already decided the answer for yourself. Are you looking for confirmation of your idea? Objectively, the bell will do nothing by itself, at least to the aim of making a trombone sound, so it's only as good as the the rest of the instrument, and the player. You can't take it out of context. This alone is enough to conclude that the answer is, "it depends", rather than that it is the majority factor in how an instrument plays/resonates/vibrates/◑◐▲△. I personally would say that since the bell is the final section of the trombone in sound production, and does nothing by itself, it might be the least important. But I also know that the trombone is a system -- every part is equally important to the final sound.

As to the second post, about how much of the original sound of a horn would be changed if you changed the bell, this is a completely different question from your OP, and also not something we can be objective about. You could argue that if the sound changes at all, it's 100% different. So a change of the bell would be a 100% change. Same with the mouthpiece, or the slide, or valve, or player.

For the OP question, about my guess, I would say the bell is about 1/3 of a trombone, so it accounts for 33.33% of the "vibrations". But it has a larger volume, so it is at least 75% of the "resonance".

[Nomsis]

I'm a physicist and so I would also like to add my two cents. (Although the answer given by LeTromboniste is pretty good already)
For the trombone to work we don't need to have the bell nor any other part of the trombone to vibrate/resonate, because the trombone is an air instrument! In short:
When you are playing you send a pressure impulse into the instrument which travels at sound velocity to the other end (aka the bell) where it is reflected by the open end (part of the energy is also radiated outwards - this is the sound we hear) and then travels back trough the instrument to the mouthpiece where it helps you sending the next pressure impulse thus leading to a standing wave in the instrument.

While this process generally works at any kind of tube obviously the shape of the tube has a great effect on the way this works. The shape of the bell helps greatly to reflect the pressure impulse back into the instrument and to also radiate part of the energy to the outside world due to its bigger diameter.
With that said its obvious that the shape is the main point of any brass instrument and anything else is secondary. This is why plastic trombones can work and still really sound like a trombone.
The material and resonance/vibration of the same can only add minor effects to the way the air is reflected on the material (not saying it is unimportant for good playing but minor with respect to the shape). This can easily be tested by wrapping some fabric around your bell which will dampen most of the vibrations of the bell and it will still sound and play like a trombone - but maybe the playing and sound characteristics will change a little.

[boneagain]

...
How much would the original sound of a horn be changed if someone only changes the valve section, vs changing the valve & the slide vs changing the entire horn?

This is a more approachable question.

Three well-established facts here:
1) a pipe closed at one end only sounds every other partial
2) the cup of the mouthpiece and flare of the bell rearrange the effective length of a pipe closed at one end such that we get an approximation of the "natural" overtone series.
3) discontinuities in the acoustic path will cause early reflections which can interfere with the standing waves gotten from #2.

So, yeah, as Nomsis asserts, this is why the plastic trombone still sounds like a trombone.

I suspect many astute listeners could identify the difference of the same pitch at the same volume played on a bass trombone vs tenor. I also suspect that most non-players would not succeed in AB blindfold tests of one large bore tenor vs another.

So sound-wise, as long as a wayward valve edge or solder blob or crunched slide crook does not cause early reflections, effects of changes other than the bell are not going to result in much change.

But from behind the horn the effects are much larger from ANY change. A disconuity has to be pretty large to be heard by the average listener. Much smaller discontinuities can have significant effects on starting notes and ease of sustaining notes.

There are interesting papers at Edinburgh about characterizing horn shape with pulse reflectometry. They bounce signals of different frequencies along the bore. Does a nice job of showing where the valves and such are. Basically, they get the number and significance of discontinuities all along the instrument.

The reason you are getting fairly complicated responses is that you asked, and continue to ask, a very complicated question. Alistair Braden on the old TTF did some excellent work on characterizing what you ask for his PhD. A high point of his research, for me, was successful prediction of sonic characteristics of a Roman brass instrument.

I do wish you luck with your simple answers, but this still remains a complex topic.

[elmsandr]

So, the problem here is really a matter of definitions and margins… if you are asking how much it changes by just swapping a bell? Almost none. Probably 99% the same even between a 2b and a 50B. Player and rough wind column shape are the most determinant factors by a wide margin. To go by analogy, if we interpret the question as how different is a commute in a Honda Civic vs Ford Expedition…. The route and speed limits are the same, if there are no odd space requirements, they both get you there on time. The pBone may sound ‘like’ a trombone, but it doesn’t feel much at all like a nice horn.

SOOO, Brian is a performer… I think you are looking for the margins to go from a pack finisher on a raceway to pole position. By the rough estimates, they still are VERY similar to the Civic and Expedition. The physics there work the same, too. But the margins are what you want to identify. I still contend that for play testing we have two distinct problems; we can’t well define what we want objectively, and it is very hard to make the measurement repeatable for a single observer or reproducible to another observer.

So, I will still stick to “it depends”, but I will continue to beat the drum that you cannot discount the statistical interactions. Seriously, do the paper airplane experiments on line… they are designed to show you that focusing on main effects only you can miss the optimal design parameters.

Cheers,
Andy

[OneTon]

I think it would be possible to make a simplifying assumption to use the ~2cm diameter exiting the tuning slide fitting and to extend that diameter to the length required to match the pitch of whatever configuration of slide, valve, and bell that it is desired to be compared to. An oscilloscope could be used to measure the amplitude of the response at each fundamental and partial frequency which could then be compared for the desired configuration and the base line. A comparison of each difference in amplitude might resolve the question as perhaps some analysts similar to a Fourier transform of the data might prove enlightening, ostensibly removing most subjectivity and ambiguity. There probably exists some digital signal processing equipment that would be easier to use than an oscilloscope.

[BrianJohnston]

Replying to LeTromboniste: I guess I meant "Vibrate" not resonate. To most professional brass players, the words resonate, radiate, & vibrate mean the same thing. I suppose I will try again with my question, can we try to keep the answers simple please? This seems to have become a much more complicated rabbit hole than I originally intended it to become.
I think your original premise/question is not so simple, and definitely not something we can be objective about. You're also going into it biased -- "we can all agree that the bell is truly the majority of [something this thread had shown that words don't describe objectively]" -- So the answers will be all over the place, and you've already decided the answer for yourself. Are you looking for confirmation of your idea? Objectively, the bell will do nothing by itself, at least to the aim of making a trombone sound, so it's only as good as the the rest of the instrument, and the player. You can't take it out of context. This alone is enough to conclude that the answer is, "it depends", rather than that it is the majority factor in how an instrument plays/resonates/vibrates/◑◐▲△. I personally would say that since the bell is the final section of the trombone in sound production, and does nothing by itself, it might be the least important. But I also know that the trombone is a system -- every part is equally important to the final sound.

I have not "decided the answer for myself", I made this post to try to figure something out that I don't know the answer to. I'm not looking for a confirmation on my "idea", i'm trying to get assistance answering an equipment question that I am having trouble putting words to. I've only started getting pickier on my equipment in the last couple of years. Why did you feel the need to mention that the bell does not do anything by itself (twice)? Wouldn't any professional trombonist know that already? I don't appreciate most of this part of your post, it's pretty aggressive, & relatively degrading for little to no reason.

[BrianJohnston]

Thank you for the other above answers since i've re-worded my question, and I apologize for the original confusion.

[OneTon]

My rough draft proposal may not be trivial but it should not be too high a hurdle either. It is possible it would fit into a master’s or doctoral dissertation for physics, computer science, electrical or mechanical engineer degree candidates at Purdue. There might be a few dollars involved. But not huge. The basic stuff should be around. It is also an opportunity for an assist from music majors and perhaps a publication opportunity for a degreed professor. If Purdue isn’t interested try University of Tulsa. They were always looking for cheap projects.

[ithinknot]

Consider the following, and their implications:

What would you consider an appropriate answer to your question?

and

Were such an answer even obtainable, what could you do with it?

(You're asking about a point of art for which the objective contributing elements are incredibly complex and not fully understood and the subjective are extremely personal. It's a great Thing About Which To Think, but not A Question.)

[timothy42b]

The material and resonance/vibration of the same can only add minor effects to the way the air is reflected on the material (not saying it is unimportant for good playing but minor with respect to the shape).

Nitpick. Not only add, and to some extent not even add, maybe. At resonant points of a coupled second system, the energy will be subtracted from the first system. Or, simplified, at frequencies where the brass vibrates, some energy must be sucked out of the wind column. As you point out, probably minor, given the large damping. Mechanical engineers frequently use this principle to fix vibrations in machinery, and if you look at high voltage lines carefully you will see vibration absorbers attached that do the same thing.

This can easily be tested by wrapping some fabric around your bell which will dampen most of the vibrations of the bell and it will still sound and play like a trombone - but maybe the playing and sound characteristics will change a little.

Yeah, tried that, wrapped some self vulcanizing rubber tape around my bell, hoping to isolate the wind column sound to hear it better. Couldn't detect any difference.

[harrisonreed]

I have not "decided the answer for myself", I made this post to try to figure something out that I don't know the answer to. I'm not looking for a confirmation on my "idea", i'm trying to get assistance answering an equipment question that I am having trouble putting words to. I've only started getting pickier on my equipment in the last couple of years. Why did you feel the need to mention that the bell does not do anything by itself (twice)? Wouldn't any professional trombonist know that already? I don't appreciate most of this part of your post, it's pretty aggressive, & relatively degrading for little to no reason.

Brian, I apologize. I didn't mean for it to come across that way, I even went back and rewrote my post to make sure it was focused on debating my thoughts. But I guess it didn't work. I'm sorry, and didn't mean to come across that way.

I love debating, and I wanted to see where you were going with your question as it evolved. Opening up an open discussion about bells with "we can all agree that the bell is ..." was why I went where I did. I hope you get your answer that you're looking for. Again, I'm really sorry.

[BrianJohnston]

I have not "decided the answer for myself", I made this post to try to figure something out that I don't know the answer to. I'm not looking for a confirmation on my "idea", i'm trying to get assistance answering an equipment question that I am having trouble putting words to. I've only started getting pickier on my equipment in the last couple of years. Why did you feel the need to mention that the bell does not do anything by itself (twice)? Wouldn't any professional trombonist know that already? I don't appreciate most of this part of your post, it's pretty aggressive, & relatively degrading for little to no reason.

Brian, I apologize. I didn't mean for it to come across that way, I even went back and rewrote my post to make sure it was focused on debating my thoughts. But I guess it didn't work. I'm sorry, and didn't mean to come across that way.

I love debating, and I wanted to see where you were going with your question as it evolved. Opening up an open discussion about bells with "we can all agree that the bell is ..." was why I went where I did. I hope you get your answer that you're looking for. Again, I'm really sorry.

We're good. It's an honorable reply & edit. I appreciate it.

[Dennis]

The free buzz measurement would be not relevant to the measurement of the instrument.

It's relevant if you're trying to estimate the transfer function of the instrument as an entity: the free buzz is the raw series input. Overlooking it because it isn't believed to be relevant to the question is exactly the kind of measurement that ends up on the regret list.

I'm dead certain there are other measurements that will end up on the regret list, but that one is too obvious to omit.

[harrisonreed]

The free buzz measurement would be not relevant to the measurement of the instrument.

It's relevant if you're trying to estimate the transfer function of the instrument as an entity: the free buzz is the raw series input. Overlooking it because it isn't believed to be relevant to the question is exactly the kind of measurement that ends up on the regret list.

I'm dead certain there are other measurements that will end up on the regret list, but that one is too obvious to omit.

Respectfully, a free buzz is not at all equivalent to the input of what creates a standing wave / sound from a trombone. It's not a part of the system that creates a good sound on the trombone.

Don't take my word for it. Look at any of the buzz / no buzz threads on this forum, and even the staunchest of buzz supporters will say that free buzzing and buzzing the mouthpiece are mechanically different from what happens in the face when the rest of the horn is attached. You need the horn and the wave in it acting back on the lips for them to vibrate correctly and the correct sound to be produced.

So, if we want to be experimental and scientific in our testing of the effects of a bell, and we think that measuring a free buzz would help us do that, we need to ensure that the free buzz would be exactly equal to whatever is happening in the face when the rest of the horn is attached for it to be useful. Or isolate the buzzing lips exactly as they act within this system, while removing the rest of the system. I personally don't think it's possible to do that.

In the interest of friendly debate, have you tried free buzzing and then putting the horn up to your face without adjusting anything? In my experience the only thing that comes out is an amplified raspberry sound.

The are enough buzz/no-buzz threads here, so let's not debate that please, but how can you show that the free buzz is something that you can isolate out of the whole system?

[BGuttman]

Here's a thought I had:

At room temperature (25 C) sound takes 8 milliseconds to travel from the mouthpiece to the bell of a trombone (in 1st position). That means there should be a minimum time to set up a note. Could this be a limiting factor in how fast we can play? Could this be a factor in how quickly a trombone "speaks" playing a part in an ensemble?

Furthering this thought, it takes only 4 milliseconds for the vibration to pass through a trumpet and 16 milliseconds to travel through a Bb tuba.

Not really directly applicable, but perhaps interesting.

[HermanGerman]

Here's a thought I had:

At room temperature (25 C) sound takes 8 milliseconds to travel from the mouthpiece to the bell of a trombone (in 1st position). That means there should be a minimum time to set up a note. Could this be a limiting factor in how fast we can play? Could this be a factor in how quickly a trombone "speaks" playing a part in an ensemble?

Yes, my fastest tongue is 120 attacks per second...

[robcat2075]

At room temperature (25 C) sound takes 8 milliseconds to travel from the mouthpiece to the bell of a trombone (in 1st position).

Is that right?

8 is a long time.

Sound travels at ~4900ft/sec

Divide the 9 ft of a trombone by 4900ft/sec and I get ~0.00183 seconds or 1.83 milliseconds?

[BGuttman]

Sound travels 1100 feet per second in air. Your sound is an air column. Yes, it travels faster in water or metal Wonder if that has an affect in creating the standing wave.

Incidentally, the speed of sound in brass is 4900 meters per second, not feet (that's about 3 1/3 times faster).

[timothy42b]

At room temperature (25 C) sound takes 8 milliseconds to travel from the mouthpiece to the bell of a trombone (in 1st position).

Is that right?

8 is a long time.

You're both wrong but BG is less wrong.

1100 ft/sec is close enough. It varies with temperature. From memory SQRT(kRT) will give you the speed at a given temperature.

But the pulse has to go farther than 9 feet. It has to reflect off the end and come back to the lip, so it's really 18 feet.

18 ft/1100 ft/sec= .0164 sec, or 16 milliseconds.

However, according to Benade, the time to reflect does have an impact in how playable an instrument is.

I refer you to Benade's Fundamentals of Musical Acoustics, section 20.9, entitled The Problem of Clean Attack. (a little dated, 1976 and a revision in 1990.) Arthur passed in 1987 though.

Paraphrasing a bit, the player must maintain the buzz without assistance until a complete cycle has occurred, and several more round trips are required before the oscillation is fully developed. In a running passage there isn't time for more than one cycle per note. But there's another problem, discontinuities in the instrument can cause false echoes that interrupt the process, and you can have an instrument that has good tone and stability but is very hard to start notes on. He goes on to talk about wave velocity vs group velocity, and says the round trip time is calculated from group velocity vs wave velocity.

[boneagain]

Paraphrasing a bit, the player must maintain the buzz without assistance until a complete cycle has occurred, and several more round trips are required before the oscillation is fully developed. In a running passage there isn't time for more than one cycle per note. But there's another problem, discontinuities in the instrument can cause false echoes that interrupt the process, and you can have an instrument that has good tone and stability but is very hard to start notes on. He goes on to talk about wave velocity vs group velocity, and says the round trip time is calculated from group velocity vs wave velocity.

...and... Tim brings it back to the "Real Bass Trombone" topic. Paraphrasing Tim's paraphrase, if I play the same pitch on a longer tube my chops will have to hold the note unsupported for a measurable number of milliseconds playing it on the shorter tube.

As Tim points out, speed of sound in air varies with temperature. For the kind of thought exercise we have here it is close enough to estimate at 1 millisecond per foot.

With that in mind, the LOWER notes won't see any difference from this effect. The longer bass trombone without a valve will have the same effective length as the "unreal" bass trombone with trigger engaged.

Upper notes, however will differ at least in ease of attack. Take A220 as an example. That frequency works out to about 4.5 ms per cycle. If the second position A220 is about 3.5" out from closed then that totals about 7" of tubing. If the F trigger is about four feet long then the extra tubing to play A220 in first position is close enough to 3.5 feet. In terms of total horn length this means the horn is around 8.5 feet long for second position A220 and 12.5 feet for first position A220. This is about one more cycle unsupported on the longer horn.

Since the BEST we can hope for is nearly two cycles unsupported this isn't highly noticeable. But a lot of little things can add up.

[timothy42b]

Paraphrasing a bit, the player must maintain the buzz without assistance until a complete cycle has occurred, and several more round trips are required before the oscillation is fully developed. In a running passage there isn't time for more than one cycle per note. But there's another problem, discontinuities in the instrument can cause false echoes that interrupt the process, and you can have an instrument that has good tone and stability but is very hard to start notes on. He goes on to talk about wave velocity vs group velocity, and says the round trip time is calculated from group velocity vs wave velocity.

...and... Tim brings it back to the "Real Bass Trombone" topic. Paraphrasing Tim's paraphrase, if I play the same pitch on a longer tube my chops will have to hold the note unsupported for a measurable number of milliseconds playing it on the shorter tube.

Good insight. That had not occurred to me. We've had some discussions about tone quality and alternate positions, but you point out that playing the same note on an upper partial means playing it on longer tubing.

That should lead to at least a small change in how easily the note articulates, not just difficulty getting the note position dialed in precisely. Apparently the perception of articulation is a large part of the perception of tone quality, as when you trim the start of the note from a recording people have trouble telling which instrument is playing.

But also there might be some implications for constant bore theory and the minor third attachment. Maybe we can't play as high on the valves as horns even if we match all the tubing. And on a double horn, I think there's a point at which they stay on the Bb side too. Of course the advantage of the G is in the mid to low range so maybe it's not a problem. I'll ask the guy who talked about this in the old forum days, he's still around.

It's easy to test the false reflection problem. I just tried playing with the spit valve open. D above the staff articulates just as easily either way. F in the staff is very very hard to start.

[robcat2075]

FWIW... here are four B flats in double trigger 7th position followed by four in normal first position. As I figure it, the TT7 note is through twice as much tubing as the 1st position note.



If we look at the wave forms, the TT7 Bb takes about about 13/100 second to reach full volume. There is a audible bounce to the attack that is hard to evade.

BbTT7.jpg

The 1st position Bb takes about 10/100 second to reach full volume.

Bb1st.jpg

There is a difference... but it is small even in this extreme worst case test. The difference in attack time (due to the length of the tubing) for most trombone notes and their conventional alternate positions is probably slight.

[2bobone]

Finally ! Some graphs !

[whitbey]

To understand, I like absurdities and extremes.

The resonance of a Pbone seems to be a bigger amount of sound is going to the player then out in front. It is resonance just funky.

And for cool resonance, try a glass. It now becomes a little bell. sounds different, but it is a way different sound then just blowing a slide. And it is so simple.

On the other hand to do it well requires someone like Jack Teagarden
https://www.youtube.com/watch?v=VXXaqgj2dkk

My thought. Resonance is from the bell mostly. And mostly, everything that is not bell changes how the bell resonates. So maybe the rubber thing on the slide stand or the slide lock does not resonate, but they may be making a change in what the horn does.

[timothy42b]

So on robcat's experiment, there is no problem getting the clean attack in 1st, but it takes roughly 5 complete cycles for full volume or complete oscillation.

In a fast jazz solo one would never be on a note that long, so it makes sense that the full symphonic wall of sound is not going to be achievable.