From "Talking at Concerts" by Loren Carroll, in Coronet, July 1937:

What kind of people talk at concerts? The kind that chatter all the time no matter where they are or the kind that are usually silent and require some particular stimulus such as a Bach figure to bring them out?

I could never find the answers. The most inveterate concert-goers proved drab subjects for interviews. Most were tongue-tied on this one subject.

[....]

Failing in my investigation I turned to another question: What do people talk about at concerts? What's behind the murmurs and whispers? Answering this took strenuous work: going to concerts regularly, twisting my neck out of shape, hopping from one place to another, hiding under seats, etc., etc. The result of all this I have embodied in my work, "The Anthology of Sp-sp-ppp." This monumental work is now complete but I have decided (in the hope that all other authors of monumental works will do likewise) to withhold publication.

(Thank you, Jonathan Caws-Elwitt!)