And it's obvious they cared about the voice range, 300Hz - 3kHz. Outside there, you're on your own.I am really, TRULY NOT OBSESSED with this topic. Just academically curious about the venerable Cobraflex.
The document above shows the FR (as the "fundamental" in a harmonic distortion plot) of a specific EV driver (University ID30C) on a Cobraflex III horn.
View attachment 314530
As the genie says in Disney's cartoon version of Aladdin:
EDIT: It's actually not too bad from ca. 300 to 3000 Hz. I suspect that those two notches are related to the folded horn configuration as @fpitas mentioned a few posts earlier.