Reading the first line, they're describing a MODEL, i.e., a computational tool that reflects what they THINK is going on in the real world. It's used to make predictive calculations. Insofar as the model makes useful and accurate predictions, it adds indirect evidence to support the belief that the components of the model, (the assumptions about real world phenomena) are accurately described. I don't know how much weight to put on this as evidence that a guitar would retain some sort of behavior memory with regard to it's vibratory characteristics over string changes. My understanding is that the differences between the sounds of different strings is just which partial harmonic overtones are emphasized and how much. All of these partials are going to be present at some amount anyhow. The soundboard still has to vibrate with all of them.guitarrista wrote: ↑Thu May 11, 2017 4:19 pmApparently there are quasi-permanent changes in the wood nanostructure dependent on moisture, temperature and stress-loading. This is probably what is referred to a guitar "opening-up" - the formation of these frozen nanostructure strains - as a result of continuous loading from the strings and possibly due to some residual drying.
In other words, the influencing factors are the usual suspects - and they do not include vibration differences from old vs. new strings
Here's an excerpt from a recent freely-available paper I found on "wood memory":
That said, ship builders have known that wood has a form of memory for millennia. The tree flexes back and forth in the wind for hundreds of years before it's harvested. Expecting a board to survive flexing in the hull for a few decades is trivial by comparison. That's a sense in which wood has "memory". The point of describing this as memory, though, is to call out the OPPOSITE behavior to what is being discussed here with respect to soundboards. Memory, here, is the lack of change in the material, not the retention of change. The point is that unlike modern composites or metals, the properties of wood stay the SAME over millions of flex cycles. That's the memory. Metals fatigue as their crystal structures change and "work harden" to become stiffer, composite polymer matrices microfracture and become softer. Wood has this form of "memory" though and bounces back to where it's always been. It stays the same, longer.
My understanding is that one of the contributing factors is that the portion of wood most useful for us is "heartwood" which is no longer part of the circulatory system of the trunk. The hollow cellulose tubules that once carried water and nutrients have long since been filled in with a dense protein called lignin. Heartwood's main role for the tree is to be like a central bony support for the living tissues on the outer surface. Lignin is interesting because, like all proteins, it's a polymer of amino acids, and adjacent chains of amino acids are linked together into a network with disulfide bridges. Disulfide bridges aren't super strong molecular bonds, but they do have some interesting properties. They can break under strain and then reform spontaneously, like magnet latches or velcro. This is one of the reasons that cyclic flexing doesn't deteriorate the overall strength of the material. It's also why heating and bending and then cooling can be used to shape wood.
Personally, I've had nothing but excellent service from Strings by Mail and I'm certain to order from them again, so a bit of self serving advertisement on their part doesn't bother me at all.