I've been digging music from the Cotton Club from the 1920s & '30s. How did those big bands perform live with a singer and have the singer be heard over the instruments? Was there amplification? Were certain vocal types preferred over others because they projected?
Great question, and I'll give a longer answer when I get home tonight. However, to tide you over, I'll blather for a moment and edit some extra info later. Early amplification was cumbersome, and would have been the responsibility of the club itself. In small venues it was often a case of just singing loud, but larger clubs might have elaborate systems, sometimes electric, sometimes an eclectic and erotic mixture of bullhorns and support systems that looked frankly rediculous. I'll see what pictures I can IG up for you later!
This is where the science of acoustics was born. Not in theaters or clubs, but in churches.