I've been going crazy with this one. Maybe someone here will remember. There were at least two "episodes" of this short (the title of which I can't remember). One took place in an elevator and another at a row of payphones. They both featured the same guy getting caught in the middle of a spontaneous piece of "music." The repeating sounds of people coughing and muttering on the phone and clicking buttons made the "music." And that's about all I remember.