Secret of the Banjo's Unique Sound Discovered By Nobel Prize-Winning Physicist 101
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.
Re:dont need to replace the drumhead.... (Score:5, Insightful)
Right... this seems like more of "A scientist that doesn't know anything about music explains something everyone who plays already knew" type of thing.
No, more like: everybody pretty much knew that the bridge being mounted on a vibrating membrane would affect the sound, but a scientist thoroughly analyzed and modeled the whole setup in order to quantitatively figure out exactly how all the parts and vibrations contributed to the sound. Then a dumbass know-nothing journalist wrote an article that misstated what had actually happened ;-)
OP is obliquely critical of Politzer (Score:4, Insightful)
! 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...