Been playing with the spoke pitch idea the past two nights for my 2nd and 3rd wheel builds (3rd is actually a rebuild where I replaced the well used factory spokes and rounding nipples with new ones)
One thing that surprises me is that most people who have looked at this seem to be using the entire length of the spoke from nipple to hub. What I find though is that I get the clearest pluck if I damp the crossing spoke with my hand, and then damping the short piece inside of the cross doesn't change anything. So I'm pretty sure what I'm getting is the resonance of the nipple to the primary cross that is actually in contact.
These are 36er wheels, so that distance is 260mm. Neglecting end effects, finding that these 2mm plain gauge spokes pluck at round 410 Hz implies around 117 KgF, which seems like a reasonable number for a heavy (42mm wide, double wall) rim. Additionally if I run the numbers for the entire length (about 350mm out of 369 ordered length) that 410 Hz would imply about 200 KgF, and there's no way that is reality.
Previous times I've done this (including a few weeks back in the field when I got some spoke noises during a climb) I didn't think to damp the crossing spoke and while I could hear some spokes plucked "off" things were much less clear. Damping the other side of the pair seems to remove that dissonance and make the situation of the spoke being plucked a lot clearer.
That said, as the wheel starts to equalize there does seem to be a "choir" effect - I'm damping the paired spoke but there are 34 others free to sympathetically vibrate - the sound does seem to be "better" when each one is tuned so it matches the rest of the wheel.