Marcel Duchamp - With Hidden Noise
Channel: Lark Wool
Date: 2012-04-06

"Before I finished it Arensberg put something inside the ball of twine, and never told me what it was, and I didn't want to know. It was a sort of secret between us, and it makes noise, so we called this a Ready-made with a hidden noise. Listen to it. I don't know; I will never know whether it is a diamond or a coin" Marcel Duchamp

"With Hidden Noise or A Bruit Secret" 
Duchamp completed with the help of his friend Walter Arensberg

ball of twine pressed between two brass plates
joined by four long screws
assisted readymade
11.4 x 12.9 x 13 cm 

Easter 1916, New York

http://www.toutfait.com/unmaking_the_museum/Hidden%20Noise.html