Looking through a book of Man Ray photographs yesterday, I came across a series of portraits of Dadaist artist and composer Kurt Schwitters. Schwitters is probably best known for his collages, but he is also the composer of the Ur Sonata, which was immortalized in Brian Eno's, Kurt's Rejoinder, from the album Before and After Science. The song features samples of a recording of the Ur Sonata in Schwitters' own voice.
I couldn't find the same images online, but I found this image that I believe was taken by his son.
It is very similar to the images in the Man Ray book. Notice his mouth. Could he be performing the Ur Sonata? In the images in the book, there were four, he had his lips pursed in a different shape in each image.
And Here is a Schwitters collage that is typical of his work.