Robert Morris 'Box with the sound of its own making', 1961

"In January 1961, the sculptor Robert Morris created a piece of art by recording the sounds of himself building a box—the racket of the saw and hammer, the quieter moments of measurement and fitting. It took around three hours. When he was done, he put the tape recorder inside the box, pressed play, and sealed it. He called the piece "Box with the Sound of Its Own Making." It is an example of conceptual art and in particular it is reflexive in that it is self referential.