Effect of mass addition on tone - Experiment Design

[sirisobhakya]

I think everyone knows already that adding a mass on various location of a horn, like heavy valve cap, counterweight, harmonic collar, etc., affects both the response and the tone color of the horn. But I have not seen any “concrete” discussion and conclusion using controlled experiment and sound analyzing techniques to interpret the results.

The response or “feel” is subjective, and I don’t plan to test that. On the other hand I have long thought about using FFT to analyze the sound. The experiment I am thinking of goes like this:

Test object - double valve bass trombone; 2 types of valve caps (normal, lightweight), counterweight (attachable to 2 braces), some weight to attach to the mouthpipe (to simulate “harmonic collar” or something along those lines), rubber tube around the bell rim to increase the weight

Primary variable - weight of the valve caps (2 normal, one each, 2 light), number and position of counterweight attached (0, tuning slide brace, middle brace), “Harmonic collar” attached (0-1), bell weight attached (0-1, or more if applicable, such as different thickness of the rubber tube)

My questions are:

1. Have anyone done this kind of experiment? Will it provide any useful result? Or is it just a silly idea?

2. For the simulation of the mouthpipe collar, I am thinking of some coins or metal pieces, or even some rubber piece snugly wrap to it with clear tape. The weight could also be attached to the rotor cap to increase weight as well. Would this work, or do you have any other idea?

3. Since the volume affects the tone, any suggestion to monitor and control the volume?

4. Any other suggestions would be highly appreciated!

Thank you very much!

[robcat2075]

I am doubtful that useful measurements can be obtained.

The perceived changes that these alterations make are already small.

To measure them you will need the human to make exactly the same input to the horn every time, which seems impossible.

And how do you prevent the player from knowing what alteration has been made for each trial?

I dimly recall some physicist-musicians creating some artificial lips for their experiments that they asserted would blow the same each time but that may never have been representative enough of real playing to be meaningful.

The unlikelihood of meaningful results should not stop you from doing it, however.

I suggest you get several trombone players who can all use the same horn and identical mouthpieces. Blindfold them and have a crew hovering around them that can quickly attach and detach the various modifications, done in some manner that does not inform the player of what has been changed.

You could collect both blind-player and blind-listener reactions and also electronic data.

[hyperbolica]

All (ok, not all, just the really long ones) arguments on trombone forum devolve into this completely futile call for a double blind study, statistically significant sample, keep all but one factors the same, etc etc etc.

I'll tell you what the results are, without any regard to which study it is: Yes, all those things make a difference - weight here and there, bell material, lacquer, bell diameter, grip tape on the neck pipe, spit valve cork twisted 17.8 degrees, even where the player is the variable, and they all just play whole notes without recording the initial articulation. Yes, all the changes make a difference, and that difference can be measured.

BUT, the difference is so small that if you're not paying attention or don't know what to listen for or don't have the right equipment set up in the right way, you might not be able to hear that 1% or .1% or even .01%.

Plus, the mic that's at the back of the hall might not pick it up at all, but a mic between the bell and the player's head might.

So it really does come back to validating your subjective experience. What you hear is what you hear. If the Harmonic Pillars or laFreque patches or Sauer brace or weights on the bell or Megatone mouthpieces make a difference to you, then there is a difference to you. You don't have to prove anything to anyone to use any thing you want to get the sound you want, even if you're the only one who hears it.

Remember, thanks to some really top notch thinking, the topics of science and economics are banned on this forum, so a real study is something we couldn't even talk about. We could solve the problem with a Ouija board, though, as witchcraft doesn't seem to be banned.

TOS excerpt:

[baileyman]

... On the other hand I have long thought about using FFT to analyze the sound. ...

Fourier? Could be interesting.

Also try zero caps.

People talk about the significance of more/less weight or material composition for parts that are easily discretely modified. Yet the remainder of parts could conceivably be modified somewhere in their middles that would make much more difference. That's much tougher.

There's a fellow out there doing adjustable in-bore reflections who claims huge results. Cannot remember a link. But the basic idea is inserting a tube with a partial obstruction that then partially reflects the standing wave, but from an unexpected and new place, not just at part junctions or bell ends. That could be interesting to measure, too.

[BGuttman]

I think Baileyman is referring to the Acousticoil. They were originally intended to place in the tuning slide. I've always felt they were "black magic" but you might find it helps you. I've heard more about them from trumpet players than trombone players (maybe that's some kind of indication).

[robcat2075]

I rather think that the ban on "science" discussions was for sciencey stuff not clearly applicable to music like evolution, global warming, poll skewing, etc... like that.

I would hope that acoustics remains a permissible topic.

[BGuttman]

There is lots of Science that is appropriate to Trombone playing. Metallurgy, Acoustics, physics of tone production, etc.

Intelligent Design, Flat Earth, and Global Warming deniers (or their opposites) will probably get at least a warning.

[hyperbolica]

Intelligent Design, Flat Earth, and Global Warming deniers (or their opposites) will probably get at least a warning.

None of that is science.

Could we at least get someone to remove "science " and "economics" from the banned list? It's embarrassing and makes trombone players or at least forum participants look stupid and afraid of math. Please? Playing trombone is a combination of material science, geometry, math and acoustics. Buying, designing or making a trombone is about half economics, along with more material science and geometry.

If you're afraid of flying pigs, say "flying pigs", not "living beings". The TOS might be trying to be general to cover all bases, but it comes off as petty and ignorant. Maybe you could say "trigger issues", but that could include Monette, BAC, Irv Karan and Quinn The Eskimo. Find a way to say what you mean. Science and Economics are central to most of what we discuss here.

[BGuttman]

Intelligent Design, Flat Earth, and Global Warming deniers (or their opposites) will probably get at least a warning.

None of that is science.

...

The opposites (at least to me) are. To some they are Science. Still, I'm probably going to shut down a discussion on human evolution as it probably doesn't pertain to trombone playing (with the exception of opposable thumbs). The economics of earning a living as a trombone player is appropriate, although a detailed discussion of Trickle Down or Milton Friedman probably doesn't belong here.

You have to trust us Moderators to make intelligent decisions. Often when we hit a gray area we all huddle up and try to make a group decision. Note that there is no guarantee of Free Speech since this is a private forum and not a public square. You participate (or don't) "at will".

[harrisonreed]

The idea that creating artificial lips that would vibrate the same way each time would give the results you want on a study is flawed.

Changing the weight of the horn in various spots necessitates or creates an opportunity to play the horn differently. If you actually could blow the same way into it each time, you'd probably find that each setup sounds bad.

Changing the horn up affects what you can do on the input side. If it feels like your chops are more relaxed and the horn can take a lot more air, whatever you changed wouldn't be measured properly if the robot lips weren't adapting and responding to that.

[Peacemate]

Changing an equation to get a better result is only useful if you know what "better" would entail. Since everyone's starting variable(s) are different you cannot really scientifically test this without doing it on every single person. At that point, why not "just" go get a horn fit to you?

A Fourier transform will relate very little to what you actually hear. Seeing lines on a screen isn't the best way to experience sound. We have ears for that, however subjective those might be.

[Burgerbob]

I think the idea of this is fun, but also... trombone playing (and music in general) is not a science. You can do studies about art and music, but the connection between the science and the part that matters- what we hear and feel- is pretty tenuous at best.

Don't let it stop you! but it may be more worth it to just play some etudes and make a great sound.

[Crazy4Tbone86]

Over the years, I have added different amounts of mass to different parts of the trombone in my never ending quest for the perfect trombone. While I believe that the science of acoustics is important in trombone design and should always remain relevant to our art, I don't think that science will give you all the answers you are looking for. How an instrument plays is a very personal and subjective thing. A trombone that I think plays wonderful......another trombonist will think is a horrible instrument. I believe every serious player should experiment and find the appropriate weight in all the components that works for them.

In my experiments, I have discovered the following. I imagine that these things can explained with physics or a mathematical equation:

*The point of diminishing returns occurs very quickly. If you add a certain amount of weight to your valve cap and get all positive results. It could very well be that adding the slightest bit more weight could completely kill the response of the horn. I've heard many people refer to this as "the positive returns suddenly fall off a cliff."

*Moving the weight the slightest bit can make big difference. A movable weight like the Chuck Ward weight (James DeSano used one of these for many years) is a great design because you can move it around to find the perfect placement where it helps the entire register of the instrument. One of my first projects when I retire will be to make a set (many 7-10) of these at graduating weights so that infinite experimenting can happen.

*Many times, a positive gain will be balanced with something lost elsewhere. If I add weight to a specific part of the trombone, there could be four or five notes that have better articulation and core. However, that weight and placement could result in four or five other notes loosing some response.

*Do acoustical experiments....especially your personal feedback versus audience feedback! Several years back, I made a few horns with extra weight spread throughout the bell section (valve cap, ferrules, thicker metal on brace tubes). One in particular had a moderate amount of weight and felt good at home. I took it to an orchestra rehearsal in a large open hall and it felt dead......I felt like I could not play comfortably above a mezzo forte. After the rehearsal, I heard from some people sitting near the back of the hall that my sound was cutting through everything and making it back there with a strong presence. Essentially, the extra weight added a tremendous amount of projection! I ended up pulling the bell apart because I could not get enough "player feedback" from it.

[andym]

Yes, you could do this experiment but except for some things that are hidden it may not be possible to completely blind the changes from the player. That’s ok. Not all medical experiments can be double blind. Some procedures just can’t be hidden from the patient or doctor. What you can do is blind the analysis from the player.

So have a player play multiple times with different valve caps, for example, measure FFTs but don’t let them see the data. While singing my wife can watch an FFT and adjust her voice to change it. She has an advantage over us. Different vowel sounds have very different spectra.

Then the experiment becomes how does playing with heavy valve caps affect a players sound. Whether or not that is the result of the valve caps or the player is hard to separate but may not be important. We care more about the resulting music than the reason.

To try and separate the effects, you could ask whether the results make theoretical sense. If the impact is opposite to the theory than it could well be the player is controlling things.

It could be very interesting to collect data from near and far from horn.

[harrisonreed]

All I know is that the harmonic brace changes the slotting like crazy on my Edwards, and wrapping up the throat is the bell changes it up too. Both in different ways.

[Kbiggs]

Years ago, I had a Bach 50B3. I experimented with some bronze bushings under the valve caps. One under the F cap, one under the Gb cap, one under each cap. It made the horn slot better, and it projected almost too well. OTOH, at times it felt like I was blowing against a brick wall. Everything makes a difference.

[andym]

Another thing to think about is how to summarize the FFT results. The spectra have so much information that it could be hard to see through to the key differences. If you could come up with two or three numbers computed from the spectra you could then plot each point on a graphs and then look for pattens in what experiments group together. If it takes more than two numbers then you can plot a series of graphs of all pairs for some exploratory data analysis.

Possibilities could be the ratio of the first and second peaks, the location of the maximum peak, a measure of the centroid of the power spectrum with respect to the first peaks frequency, or shape parameters of a function that is fit to the various peaks.

Figuring out measures that correspond to our subjective judgements of warm or dark sound could be a good starting point. I imagine someone has worked on that.

[whitbey]

Adding mass to a horn can make a difference.

Edwards pillars are pretty impressive with a small amount of material. When I first got a single pillar valve I tried all the variations with a touch of wonder. Then I put a few bolts both quality and cheap in. Those bolts ruined the play of the horn. To me proving the benefits. I found a setup I like and have not changed it for years.

I found on my Edwards horn that I play straight that placing the weight closer to the neck pipe rather then centered made the horn play better.

I found that the aluminum Rath style brace placed on the horn just above the sound pillar on my Edwards or the brace on my Bach bass had no noticeable effect on the play or sound. Probably that is a aluminum thing.

I added copper washers under my valve caps on my Cerveny euphonium. I liked the color of the sound better and way it played. The washers were cheap and easy.

Where on the horn and what on the horn probably has as much variable as anything. This is a science that is so complicated that working it as an art is more practical.