What do you mean by "a piece of 'music concrete'"? If you're advocating the creation of a performance piece which incorporates unfortunate public noises such as coughing and paper rustling, how would this alleviate the irritation which arises when those noises pop up during more classical performances? Since the very nature of such noises is (usually) accidental, creating a space specifically for such noises isn't going to detract from the likelihood that I'll hear those same sounds at the theater.

How about noise-cancelling technology being used in such a space, that cancels out all coughs, candy and farting?