The film takes place in two worlds: the Real World and the Rest. The Deems Taylor interstitials represent the Real World, while all the individual episodes take place in a different subworld of the Rest. The intermission takes place entirely within the Real World, and it has two components, the jam session and the segment about the soundtrack.
The sound-track segment has a clear function. The film as a whole consists of images set to sound. Each episode is based on a piece of music, sound, and each takes place in a different imagined world, images. The soundtrack segment is a lesson on the relationship between sight and sound. The soundtrack segment clearly takes place in the Real World. Taylor is right there coaxing the soundtrack into performing for us.
The soundtrack segment is preceded by the jam session. The intermission segment opens on a stage, I believe, with musicians in place. The clarinet and bass start it off and the others join in.. When Deems Taylor comes on stage, he coughs and thereby shuts it down. We are thus being explicitly told that the jam session doesn’t come from Taylor; on the contrary, there is some kind of (possibly mild) opposition between the two.
That, in effect, establishes music as the spontaneous foundation of the imaginative worlds we see in the rest of the film. Once that has been done, THEN Deems Taylor gives us his little demonstration of the relationship between sound and image. Taken together these two segments anchor the rest of the segments in here-and-now reality. They establish the imagination, and art, as being central to the Real World.
Thus goes Disney’s lesson in metaphysics.
* * * * *
This little argument should be applied to the arguments in these longer posts: