To what extent did music transform ideas about race? The answer could be "not at all" to "entirely." To the extent that it did, New Orleans music mattered.
Here is a really cool piece on the relationship between Louis Armstrong and Bing Crosby. The two first met in 1926 in Chicago and became lifelong friends.
Bing as part of the Rhythm Boys in The King of Jazz (1930)
Armstrong in Copenhagen in 1933
With Bing in 1956 in High Society.
Ella Brennan on Louis Armstrong
Way down yonder in New Orleans from Loyola DOHS on Vimeo.