What is a banjo?‏

Banjo timbre from string stretching and frequency modulation

David Politzer

California Institute of Technology

(Dated: June 20, 2014)

http://arxiv.org/pdf/1406.4907.pdf

The geometry of a floating bridge 

on a drumhead soundboard 

produces string stretching 

that is first order 

in the amplitude of the bridge motion. 

This stretching modulates the string tension 

and consequently modulates 

string frequencies at acoustic frequencies. 

Early work in electronic sound synthesis 

identified such modulation 

as a source of bell-like and metallic timbre. 

And increasing string stretching 

by adjusting banjo string-tailpiece-head geometry 

enhances characteristic banjo tone.

Hence, this mechanism 

is likely a significant source 

of the ring, ping, clang, and plunk 

common to the family of instruments 

that share floating-bridge/drumhead construction.

________

 Who is David Politzer 

Born 31 August 1949, is an American theoretical physicist

who shared the 2004 Nobel Prize in Physics with David Gross and Frank Wilczek 

for their discovery of asymptotic freedom in quantum chromodynamics.

Politzer was born in New York City. 

His parents, Alan and Valerie Politzer, 

immigrated to the U.S. after World War II and were both doctors. 

He graduated from the Bronx High School of Science in 1966, 

received his bachelor's degree from the University of Michigan in 1969, 

and his PhD in 1974 from Harvard University, 

where his graduate advisor was Sidney Coleman.

In his first published article, which appeared in 1973, 

Politzer described the phenomenon of asymptotic freedom: 

the closer quarks are to each other, 

the weaker the strong interaction will be between them. 

When quarks are in extreme proximity, 

the nuclear force between them is so weak 

that they behave almost like free particles. 

This result—independently discovered 

at around the same time by Gross and Wilczek 

at Princeton University—was extremely important 

in the development of quantum chromodynamics. 

With Thomas Appelquist, 

Politzer also played a central role 

in predicting the existence of "charmonium", 

a subatomic particle formed 

of a charm quark and a charm antiquark.