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Secret of the Banjo's Unique Sound Discovered By Nobel Prize-Winning Physicist
KentuckyFC (1144503) writes The banjo is a stringed instrument that produces a distinctive metallic sound often associated with country, folk and bluegrass music. It is essentially a drum with a long neck. Strings are fixed at the end of the neck, stretched across the drum and fixed on the other side. They are supported by a bridge that sits on the drum membrane. While the instrument is straightforward in design and the metallic timbre easy to reproduce, acoustics experts have long puzzled over exactly how the instrument produces its characteristic tones. Now David Politzer, who won the Nobel prize for physics in 2004, has worked out the answer. He says the noise is the result of two different kinds of vibrations. First there is the vibration of the string, producing a certain note. However, the drum also vibrates and this pushes the bridge back and forth causing the string to stretch and relax. This modulates the frequency of the note. When frequency of this modulation is below about 20 hertz, it creates a warbling effect. Guitar players can do the same thing by pushing a string back and forth after it is plucked. But when the modulating frequency is higher, the ear experiences it as a kind of metallic crash. And it is this that gives the banjo its characteristic twang. If you're in any doubt, try replacing the drum membrane with a piece of wood and the twang goes away. That's because the wood is stiffer and so does not vibrate to the same extent. Interesting what Nobel prize-winning physicists do in their spare time.
The frog who plays banjo...
live:
https://www.youtube.com/watch?v=d-ZFg5-oaS0
the studio version is tighter:
https://www.youtube.com/watch?v=qKQWhsLbe9E
can't decide which I prefer.
Get thee glass eyes, and, like a scurvy politician, seem to see things thou dost not.--King Lear
Banjo is for robots.
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You just can't sing a depressing song when you're playing the banjo. You can't go-- "Oh, murder and death and grief and sorrow!" --Steve Martin http://snltranscripts.jt.org/7...
The drum membrane is made out of 'possum skin.
Just hold a thumb against it. a Lot of us players do that to adjust the sound for different "expression"
Do not look at laser with remaining good eye.
So I guess this will get him an Ig Nobel prize for finding out why a banjo sounds like a banjo?
I've heard some of them are still searching for that elusive Gräfenberg spot in their spare time.
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I think he's just going for the Ig Noble prize.
If you're in any doubt, try replacing the drum membrane with a piece of wood and the twang goes away.
The evidence is that if you change a fundamental part of the instrument, it no longer has its distinctive sound? I think we could have guessed that much.
Bastard ruined all the fun of a great musical instrument that has stood the test of time and silenced its harmonious metallic twang just to reinforce his own intelligence to the public ear.
I hope someday some bored hillbilly discovers a way to use fried chicken to prove that David Politzer was nothing more than a hack who ripped off the ideas of some crazy back-hills mountain man who was the real brains behind quantum chromodynamics.
now explain the sitar...
Doesn't he have anything better to do?
One point is that it is the disability of human hearing which enables hearing the metallic character of the banjo. Brass wind instruments are also subject to human, hearing limits as the player receives some of the sound through the jaw bone vibrations, and also hears sounds projected by the body of the instrument whereas the audience hears what is projected from the bell of the instrument. As the hearing of each player is different players tend to get overly concerned about brand and model of an instrument as their own ears deceive them a bit. Sometimes the player may feel that he did not play all that well and yet the audience is very impressed and the reverse can also be true.
noice! mechanical FM synthesis :D
we got a live one here.
yes but have you written it down? have you done the math behind it?
here is the original paper http://arxiv.org/pdf/1406.4907...
So the banjo is acoustic frequency modulating. When was the first electronic FM synth invented? It would be interesting if some engineers could take this one step further and create a mechanical FM synth. How high a frequency could you get, and what kind of sounds could you build?
Q: How can you tell if the stage at a Bluegrass concert is level?
A: The banjo player drools out of both sides of his mouth.
One day my old pal David has played a gig with some local musicians, including his roommate, Bob, who was a banjo player. After the set, Bob was going somewhere else with some other people, so he asked Dave to take his banjo home for him. On the way home, David stopped at the convenience store to get a six pack. As he was standing in line, he suddenly realized that he had left the car windows down, and that he was in a bad neighborhood. He rushed out, but, sure as hell, the worst possible thing had happened - exactly what he was afraid of - someone had spotted the open car windows, and thrown two more banjoes in the car.
There is no God, and Dirac is his prophet.
! Interesting what Nobel prize-winning physicists do in their spare time. !
This tells the tail of an inquiring mind that turns it's focus on many things. He reminds me of Fenman, among many similar Nobel Laureates, whose curiosity was not limited by a 9-5 mentality, but was active 24/7.
It is this quality that produces the Nobels...
The sitar has several things going on with it
Indian classical music theory is complex, at least as much as European classical music theory or jazz. There's a lot of stuff about "ragas", which are a combination of a scale or scales, melodies, fixed parts and improvised parts, with a lot of rules about which ones are appropriate for which situations.
Bill Stewart
New Fast-Compression-only CPR http://preview.tinyurl.com/dy575ks
That's what all the weird minor keys and modes are for.
Bill Stewart
New Fast-Compression-only CPR http://preview.tinyurl.com/dy575ks
Most of them can be recycled easily between genres; the drummer jokes (or bass player jokes) are more likely to be about the players, while the others are more likely to be about the instruments themselves, but either way.
I did see somebody the other day with a t-shirt captioned "First violinist problems", showing a musical staff and a note about 10 lines above the staff.
Bill Stewart
New Fast-Compression-only CPR http://preview.tinyurl.com/dy575ks
Myself and many other banjo enthusiasts have known this for years. Why is this news?
In some sense it is not a surprise because his main work was on vibrating electromagnetic fields, and the natural modes of vibration of circular membranes is a very good way to practice the mathematics of vibrations.
sed -e 's/Chuck Norris/Rajnikant/g' joke > fact
Your investment portfolio isn't paying out like you'd hoped, guy?
Richard Feynman enjoyed playing the bongo drums, picking locks, and whatnot; and also
Then I had another thought: Physics disgusts me a little bit now, but I used to enjoy doing physics. Why did I enjoy it? I used to play with it. I used to do whatever I felt like doing - it didn't have to do with whether it was important for the development of nuclear physics, but whether it was interesting and amusing for me to play with. When I was in high school, I'd see water running out of a faucet growing narrower, and wonder if I could figure out what determines that curve. I found it was rather easy to do. I didn't have to do it; it wasn't important for the future of science; somebody else had already done it. That didn't make any difference. I'd invent things and play with things for my own entertainment.
So I got this new attitude. Now that I am burned out and I'll never accomplish anything, I've got this nice position at the university teaching classes which I rather enjoy, and just like I read the Arabian Nights for pleasure, I'm going to play with physics, whenever I want to, without worrying about any importance whatsoever.
Within a week I was in the cafeteria and some guy, fooling around, throws a plate in the air. As the plate went up in the air I saw it wobble, and I noticed the red medallion of Cornell on the plate going around. It was pretty obvious to me that the medallion went around faster than the wobbling.
I had nothing to do, so I start to figure out the motion of the rotating plate. I discover that when the angle is very slight, the medallion rotates twice as fast as the wobble rate - two to one [Note: Feynman mis-remembers here---the factor of 2 is the other way]. It came out of a complicated equation! Then I thought, ``Is there some way I can see in a more fundamental way, by looking at the forces or the dynamics, why it's two to one?''
I don't remember how I did it, but I ultimately worked out what the motion of the mass particles is, and how all the accelerations balance to make it come out two to one.
I still remember going to Hans Bethe and saying, ``Hey, Hans! I noticed something interesting. Here the plate goes around so, and the reason it's two to one is ...'' and I showed him the accelerations.
He says, ``Feynman, that's pretty interesting, but what's the importance of it? Why are you doing it?''
``Hah!'' I say. ``There's no importance whatsoever. I'm just doing it for the fun of it.'' His reaction didn't discourage me; I had made up my mind I was going to enjoy physics and do whatever I liked.
I went on to work out equations of wobbles. Then I thought about how electron orbits start to move in relativity. Then there's the Dirac Equation in electrodynamics. And then quantum electrodynamics. And before I knew it (it was a very short time) I was ``playing'' - working, really - with the same old problem that I loved so much, that I had stopped working on when I went to Los Alamos: my thesis-type problems; all those old-fashioned, wonderful things.
It was effortless. It was easy to play with these things. It was like uncorking a bottle: Everything flowed out effortlessly. I almost tried to resist it! There was no importance to what I was doing, but ultimately there was. The diagrams and the whole business that I got the Nobel Prize for came from that piddling around with the wobbling plate.
-- Surely you're joking, Mr. Feynman (c) 1985, PP 157-158
Florian Pfeiffle and Rolf Bader wrote a paper called "Real-Time Physical Modelling of a complete Banjo geometry using FPGA hardware technology" that explores this:
http://www.systmuwi.de/Pdf/Papers/Bader%20papers/Physical%20Modeling/PhysicalModeling_Banjo/Pfeifle,Bader_04FPGA_Format.pdf
This effect on timbre is well known and was the basis for the range of Yamaha DX synthesizers in the 1980s. Basically when a tone is modulated (pitch changed) at high speed, instead of hearing a vibrato, you hear it as additional overtones, i.e. a change in the quality (timbre) of the sound. This technique is called Frequency Modulation (FM). It's especially useful for generating metallic and bell-like tones, like the famous FM electric piano sound of the 1980s.
The vibration of the drumhead at audio frequencies causes additional overtones through an FM effect. Damping the drumhead (or replacing it with a solid alternative) eliminates this effect and the additional overtones created. This is basic synthesis theory that any keyboard player would know.
Unsurprisingly, FM synthesizers can do a very convincing banjo copy.
Does it need to be written down? It wasn't like the banjo was accidentally made... it was designed that way. That is why there are all sorts of hybrid instruments, like the Dulcijo (dulcimer banjo), where the whole body is designed to be just like a normal dulcimer except for the bridge, which sits atop a tiny drum head like a banjo does.
Bridge+vibrating support for the bridge + vibrating strings = banjo sound has been no big secret for a long time.
It is neat he did math behind it, but the summary makes claims about how mysterious it was, and that sounds pretty ridiculous.
while(1) attack(People.Sandy);
Actually the highest priced banjo on eBay is currently going for $24,900. Some vintage 5 strings sell for ca. $75k or more; by my informal estimate your average bluegrass musician spends about $1.5k on their instrument, some more than that. Contrast that with how you can buy a serviceable electric guitar at box stores for $200. I don't know what the typical rocker is spending these days, and indeed some spend tens of thousands on old Fenders and Gibsons, but I'd reckon that bluegrass banjo players are anything but poor.
bunka-bunka-dinky-dinky-KHALISTAN ZINDABAD!
well some violin sell for millions
It is neat he did math behind it, but the summary makes claims about how mysterious it was, and that sounds pretty ridiculous.
And that is the nature of science reporting these days. The original paper doesn't call it a mystery, and at most says it is a "reasonable question" to ask what quantitatively distinguishes the sound of the banjo family of instruments from other stringed instruments. If the PR machine picks up on a paper though, even the smallest of incremental improvements that has heavy citations in the original paper (even right in the abstract...) to previous work, the scientist's work suddenly becomes solving the greatest unsolved mystery in their field. While it is one thing to drum up interest in science, frequent trends like that give a false impression of what science work is really like, where a large number of scientists are busy slogging out the details and improving on previous work incrementally most of the time.
No offense, but this was a complete waste of an article. You ask anyone associated with making this or any stringed instrument and they could have easily given you the answer. There's reasons why instrument makers use or experiment with different bridge, body, fret board, the frets themselves with different materials. Most stick to standard materials. I've seen Banjo's in slow motion and can easily see how the details, such as the vibrations from the entire instrument.
Just because the guy is a Nobel peace prize winner, this doesn't make him the only person on the planet to have figured this out. And I'm sure because this is a geek and nerd site everyone will pretend as if this story and the man behind the -already known- reasons for a Banjo's tone, he will be immediately worshiped.
Here is a similar recent article analyzing the sound made by a bouncing basketball:
http://arxiv.org/pdf/0808.3278...
WTF? I've played string instruments for many years, and I'm astonished that it took so much research to prove what those of us that pley the banjo always knew.
Between a banjo and an onion? ;-)
Nobody cries when you cut up a banjo.
I would never have guessed.
"The banjo is a stringed instrument that produces a distinctive metallic sound often associated with country, folk and bluegrass music. It is essentially a drum with a long neck."
WTF? Who could NOT know this?
What is the difference between a banjo and a motorcycle?
You can tune a motorcycle.
Contrast that with high end new archtop guitars selling between $30-60k and vintage ones where the sky is the limit.
Truthfully, you can get most instruments in a variety of price ranges, dependent on your needs or vanity.
The short lifecycle of a $200 instrument usually ends up in a spare parts drawer. Most instruments over $10k don''t see much more action than the studio or a display case. A good all round workhorse guitar for most uses SHOULD weigh in around $3-5k, the higher end of "off the rack".
A good banjo should bring enough at pawn to bail its owner out of jail as a general rule.
*Repent!Quit Your Job!Slack Off!The World Ends Tomorrow and You May Die!
Is it fair to say he discovered this secret? I respect his status as a nobel prize winner, but could he not have simply publicized this knowledge? It is far more likely that a banjo player or maker has long since discovered this fact about their instrument and has even related the concept to others. I know the voice of an honored somebody will always be louder than that of an honest nobody, but still the headline does seem to eschew impartiality in favor of spectacle.
For the 5-string banjo?
That plunking sound...
Do you have room in your heart for the 5-string banjo?
It's round...
The vast majority of people involved with such instruments, including those that make them, are not going to give you quantitative answers or any answer involving math to questions about the instruments (the most consistent exception being engineers and hobbyists working on making synthesizers). A lot of design work in musical instruments is a mix of tradition and phenomenology, which in the end works quite well as people can be quite skilled at making them without sitting down to treat the problem like an engineer would with modeling, etc (not to say that some don't take a more quantitative approach). .
I used to work in a physics department at a university with a strong music program, and spent time volunteering for physics outreach. It didn't take long before you could pick out the people who were from the music program (more often the professors and their variety of friends from the industry than the students) because they would stop and ask a variety of in depth questions about some of the wave based demonstrations, while others would just stare and not say anything more than "oh cool." These people knew basic principles of things, but were interested in the details, especially how to predict and understand things without just trying things out. A favorite was the generations of patterns in sand using different vibrating shapes, which while familiar to many of them, they still would spend a long time talking and asking questions about how the structures form and the relationship between different modes, etc. They know about harmonics and at least the image of 1D and 2D modes, but don't know about solving for eigenmodes and how to get the relative strength between them, coupling, etc., beyond knowing that certain things just work.
In this case here, it looks like some professor just has a hobby and decided to write up a bit about it. He seems to have an interest in string instruments, and on his website has images from a collection and talks about doing restoration work on them. The paper he wrote doesn't make any grandiose claims, just a typical introduction and some brief work he did figuring out the why the sound is distinct and reproducing it through software. I don't even see if this was actually published anywhere other than just uploaded on arxiv. Plenty of physicists have hobbies, and get around to applying their physics background. Sometimes this spills over into examples used in classes or in special topic courses for people with similar interest (a lot of universities have someone teaching an electric physics of music course) other times it just ends up on a blog or a collection of write-ups. Medium here seems to be the one that applied the usual problems of the science news cycle (and wouldn't be the first time...), turning some physicist doing something for fun on the side into a bunch of hyperbole.
My bucket list is complete.
I wouldn't call any guitar in the $200 price range "serviceable" for any player past the beginner stage. Most of my own guitars, both acoustic and electric, retail for $1800 and up, although I have a couple of good ones at around the $800 mark.
"...acoustics experts with too much free time have long puzzled over exactly how the instrument produces its characteristic tones."
Yamaha's iconic DX7 keyboard broke new sonic ground with its "FM synthesis" model, which allowed a note to be frequency-modulated at any desired rate and amount. This gave it the ability to make those "clangy" tones that are so characteristic of FM, and that are apparently produced naturally by the banjo.
Overheard at banjo manufacturers worldwide:
Gentlemen, we now have the technology to make a banjo that doesn't sound sucky!
But then how would anyone know it's a banjo?
That is all.
Confirming he got a Nobel prize for something real and not figuring out how a man made musical instrument works.
How long before before we field a serviceable apology?
tone
I'm a banjoist and can ascertain that banjos are not cheap. Historically, they were, but as with most things, they are now made with superior woods and such. My last expensive banjo was 850$ and 20 years old.
It's been known for a while that if you place a banjo mute or any other metal object directly on the bridge, not only does it mute the volume but it also eliminates the characteristic, metallic ring. Placing objects anywhere else along the strings, pot, or even on the drum has little to no effect. The "valley" created by the bridge pressing into the drum is surprisingly small, so only a very small area of the drum affects the behavior of the bridge.
The bridge is what defines the sound of the banjo, and using differently shaped bridges has a bigger impact than using different drum materials.
It's a shame I lost most of the strength in my fingers over the years. I tried different setups for my banjo, but I could never actually play it. It's a wonderful and fascinating instrument.