The pitch actually has nothing to do with the stiffness of the spoke. (It definitely has nothing to do with the strength, which only matters when it yields.) The note is set by the inertia of the spoke going side to side, and the tension. You can do the math, the formulas are here:
https://en.wikipedia.org/wiki/String_vibration.


The John Allen article is here. His table corresponds to more or less the same kgf for straight and DB, 135-140 ish. That's the same kind of number you see from rim manufacturers. That means the DB spokes get higher strain, about 50 Mpa, he quotes strength as 150 Mpa or higher which is pretty plausible. Steel is amazing stuff.
Bicycling - Wheelbuilding: check spoke tension using musical pitch

I found lately that the Gates belt drive tension app for smart phones works fine for this, if you want to do it this way. There are also guitar tuning apps.