Tubas, Resonance, and Accoustics: Quantifying a tuba (sans player)

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Ben
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Tubas, Resonance, and Accoustics: Quantifying a tuba (sans player)

Post by Ben »

Hello all:

All this talk about science and tuba got me thinking and brought me out of my lurking. We have all seen Rick Denny's 186/York master comparison... It is interesting, but I've always wondered if player input, bias, volume, or mic placement might have skewed the results. I am certain that Mr. Denny attempted to minimize this... but human error is always a concern. Additionally, it is a small sample size.

I am interested in taking an acoustic snapshot of a LARGE variety of horns, with no player input. I don't know how familiar many of you are with sound engineering, but often, when setting up a PA, the engineer will generate a sweep tone, and record it - to EQ out oddities in a room. I happen to have an IK - Loud MTM speaker set at home that calibrates this exact same way to aid in audio mixing a few projects. These near field monitors have internal circuitry to automatically correct for accoustic oddities across the aural band. So... what would happen if you were to take a similar technology: a well calibrated speaker at a fixed length from a tuba bell, and record the sweep tone at the reciever? Would the accoustic profile (captured for each valve combination) provide an diagnostic comparison between models of tuba/specimins? Would it help explain why a certain valve combination is a challenge to play at certain registers? Would it show a leak somewhere in the horn over its age? A fingerprint if you will as it ages? Would you be able to learn that certain tubas "types" respond to your accoustic input better than others?

This is a curiosity at the moment. Musings of a mad man. Thoughts appreciated!
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Re: Tubas, Resonance, and Accoustics: Quantifying a tuba (sans player)

Post by GeoffC_UK »

I am no acoustic engineer, but I am an engineer.
FIRST OBSERVATION
In engineering we "calibrate" instruments. We calibrate them, say, every year.
This involves testing an attribute of that instrument against a known (validated) standard.
In calibration "human error" is also taken into account, if it plays a part in the outcome of that calibration.
It could mean 2 different people taking the same measurement, later comparing any discrepancy between the two readings.
SECOND OBSERVATION
In engineering we study "variation" and, for highly regulated industries, we try our best to manage it and reduce its impact on quality.
In what can be described as "artisan" tuba manufacture there will be lots of variation, some subtle & others not.
That is why one tuba next to another tuba, of same the model, may sound very different, even if blown by the same player, same room, same everything....
In the hands of a great "artisan" maker, you get the greatest of musical instruments, eg. Stradivarius.
The more that production quantities increase, the greater the difficulty in maintaining quality of a great instrument. More "artisans" are needed and some may not be as good as the Master maker.
I am guessing Yamaha are less "artisan" than many other instrument makers(?).
THIRD OBSERVATION
Years ago when I visited Boosey & Hawkes in Edgeware (London) they had some acoustic contraption fitted to the receiver of a trumpet.
Not sure exactly what it was doing, but it made a humming noise which changed frequency from time to time during the test.
FINALLY
I think the engineering and science of brass instruments (and their manufacture) is absolutely fascinating.
If I were young, again, I could easily scope a doctorate or two around a few topics that would be enlightening.
May be if I win the lottery.........

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Brass wind instrumetsn, Resonance, and Accoustics

Post by Robert Tucci »

The following link covers the subject in detail.

Highly recommended reading.

http://newt.phys.unsw.edu.au/jw/brassacoustics.html

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Re: Tubas, Resonance, and Accoustics: Quantifying a tuba (sans player)

Post by peterbas »

Ben wrote: Wed Jan 13, 2021 9:36 am Hello all:

All this talk about science and tuba got me thinking and brought me out of my lurking. We have all seen Rick Denny's 186/York master comparison... It is interesting, but I've always wondered if player input, bias, volume, or mic placement might have skewed the results. I am certain that Mr. Denny attempted to minimize this... but human error is always a concern. Additionally, it is a small sample size.

I am interested in taking an acoustic snapshot of a LARGE variety of horns, with no player input. I don't know how familiar many of you are with sound engineering, but often, when setting up a PA, the engineer will generate a sweep tone, and record it - to EQ out oddities in a room. I happen to have an IK - Loud MTM speaker set at home that calibrates this exact same way to aid in audio mixing a few projects. These near field monitors have internal circuitry to automatically correct for accoustic oddities across the aural band. So... what would happen if you were to take a similar technology: a well calibrated speaker at a fixed length from a tuba bell, and record the sweep tone at the reciever? Would the accoustic profile (captured for each valve combination) provide an diagnostic comparison between models of tuba/specimins? Would it help explain why a certain valve combination is a challenge to play at certain registers? Would it show a leak somewhere in the horn over its age? A fingerprint if you will as it ages? Would you be able to learn that certain tubas "types" respond to your accoustic input better than others?

This is a curiosity at the moment. Musings of a mad man. Thoughts appreciated!
I think it would work better if you could stick an earbud in the reciever. Because when you leave the tuba open on both sides it isn't the same like playing the tuba. You probably need a lot more power to get a standing wave and since the standing waves of different frequencies don't all end at precise the end of the bell it could be difficult to get good readings.
The earbud can be equalized with this freeware https://medium.com/@jaakkopasanen/make- ... bd567832a9
The output at the bell can be measured with this freeware https://www.roomeqwizard.com/

You could also buy this https://www.artim.at/?page_id=8&sprache=2 if you want to spent some money for the real thing.
Here some research that uses this device.
http://collections.nmmusd.org/UtleyPage ... ticle.html
https://www.researchgate.net/publicatio ... parameters
http://www.acoustics.ed.ac.uk/wp-conten ... h_2006.pdf
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