Just a theory but I'm also 100% sure it's true

https://lemmy.curiana.net/post/450159

I’d say it’s a curve.
This could be log scale. Or inverse log idk which way you want the curve to be
dB is already log scale

Boring response: I mean, dB is calculated as a function of log, but when it’s on the X axis I imagine it’s typically displayed linearly

Funny response: loglog

Loglog is what came to my mind as well.