Slashdot Mirror
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.
Get free satoshi (Bitcoin) and Dogecoins
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.
I've heard some of them are still searching for that elusive Gräfenberg spot in their spare time.
Get free satoshi (Bitcoin) and Dogecoins
I think he's just going for the Ig Noble prize.
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...
I was thinking the same, it really doesn't take a rocket scientist to figure out a banjo has dual harmonic vibrations. Duh, it has a drum and some strings. Maybe he should patent-troll it so he can try and collect for every banjo ever made.
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.
Yeah, that asshole better apologize wasting your precious /. time with his irrelevant, unapproved research. How dare he!!!
! 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
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
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.
I just don't see how this is really news of interest. I mean, good for him if he wanted to figure it out, but the discovery does not warrant coverage just because he's a nobel prize winner.
Nah, he's studying liberalism. It's important to understand the enemy's ego-driven, self important, aggrandizing motivations, faux sophistication, and how they interact with the inherent fallacies of marxist ideology. Then we can change pre-K education to keep kids off the path of professional victim degeneration and concern-troll lawyering, and focus them towards independent thought and critical thinking, where fallacious sacred cows, like consensus and feelings, don't take precedent.
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);
As I pointed out elsewhere, it is common knowledge to traditional music makers that a vibrating bridge makes the banjo sound. That is why there are instruments like this:
http://www.gardnersdulcimer.com/data/Images_Additional/dulcijo3.jpg
Designed just like this:
http://gibsondulcimers.com/In%20Stock/Baritone%20Dulcimer%2047609/Baritone%20Dulcimer%2047609%20Front.jpg
Except, big surprise, they put a tiny drum head only under the bridge so that the bridge could vibrate and make a more banjo-ey sound.
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.
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.
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!
Acid. That explains Harrisons early use anyway. There were others, but without copious amounts of acid on both the player and the listener, it fell out of favor. Now, the scientist that invented acid, Hoffman - that's the guy you want to read about.
"...acoustics experts with too much free time have long puzzled over exactly how the instrument produces its characteristic tones."
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.
How long before before we field a serviceable apology?
tone
The size and construction of the head probably makes quite a lot of difference. I have an old Dallas D banjo ukulele (a George Formby branded one, no less) and the head had an inner hoop in it which makes the effective area of the head a bit smaller than the entire diameter. As such the overtones are softer and it sounds less "banjoey" (but still very different from a standard ukulele). The other consequence of the banjo uke head is that if you play a chord like F# where one string is not strummed, you need to mute the string that's not played otherwise the head will cause the string to vibrate and make the chord sound awful.
Oolite: Elite-like game. For Mac, Linux and Windows
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.