Alvin Lucier is a composer of experimental music and sound installations whose main field of exploration is the acoustic phenomena and auditory perception. I am sitting in a room (1969) is one of Alvin Lucier’s best known works, featuring Lucier recording himself narrating a text, and then playing the recording back into the room, recording it again. This new recording is played back and recorded again, repeating this process over and over.
Every room has different resonances due to its physical characteristics, so the objective of this piece is to emphasize certain frequencies as they resonate in the room, until eventually the words become unintelligible, replaced by the pure resonant harmonies and tones of the room itself. In fact the recited text by the composer describes this process in action:
“I am sitting in a room different from the one you are in now. I am recording the sound of my speaking voice and I am going to play it back into the room again and again until the resonant frequencies of the room reinforce themselves so that any semblance of my speech, with perhaps the exception of rhythm, is destroyed. What you will hear, then, are the natural resonant frequencies of the room articulated by speech. I regard this activity not so much as a demonstration of a physical fact, but more as a way to smooth out any irregularities my speech might have.” 
Lucier also specified that the performance of this piece did not need to use his text and the performance may be recorded in any kind of room.
In its repetition and limited means and in its ambient conversion of speech modules into drone frequencies, the piece unites the two principal structural components of Minimal music in general.
 Album notes online: http://www.lovely.com/albumnotes/notes1013.html