Website alert: To supply a detail in a story, I was looking at images of street sellers in The Cries of London at the British Library. The playbill seller interested me, but I didn't see any way to download the page from the British Library site. A quick web search led me to this reproduction of the same plate at the Sound and History site—and, wow! all kinds of useful material for the historical novelist!
Imagining the sounds of a milieu is very helpful in world building, and sources don't even have to be specific to the era you are writing about. Petticoat Lane Traderss, for instance, provides a general rumble and a rough-edged insistent voice that could be used for a crowded marketplace anywhere, anytime, as well as at an auction in the 1940's. Anyway, lots to explore.