I'm listening to one of the several versions of Schoenberg's Pierrot Lunaire I have on iTunes. The sparseness of the instrumentation emphasizes each musical object starkly. The music has that menacing yet ridiculous, menacingly ridiculous quality of really good clowns. Menacing intimacy. It's like sitting in a very small theater, right up close to the performers. (There's something about Lucy Shelton's version that's razor sharp in this respect, by the way.)
What are we listening to when we listen to Expressionist music like this or look at Expressionist art? It's on the edge of beauty and the grotesque constantly. It's the most mysterious music I've ever heard in my life.
It's not really just conveying a human inner state, is it? In some sense that human state has been reduced to a menacing caricature, as in the paintings of Otto Dix. We're also hearing the clarinet as clown, the piano as high wire artist.
I think it might be object-oriented music. Music from the carnival of things.