I am reading a jazz book, "Really The Blues" by Mezz Mezzrow, in which a 1920's cornet player, Bix Beiderbecke, was referred to as playing his horn mostly " open".
He played mostly open horn, every note full, big, rich and round
I'm assuming this is a sort of slang in jazz for a certain style of cornet. I understand that the Bb cornet overtones are C, G, C, E, G with no valves pressed. Has anyone heard the term "open" style?