Variations in wood density affect vibrations, and therefore, sound.
When scientists first analyzed the wood of the vintage Cremonese violins in compared with the modern violin wood, they calculated the average density and found no difference.
Later, other researchers measured the density differential and found a significant difference.
Modern violins had a greater variation, a larger differential.
Student: So you mean the density of the wood in the Cremonese violins is, is more uniform?
Student: But Northern Italy isn't in the tropics.
Professor: No. But climate matters.
Turns out the Cremonese violins were made from trees that grew during a Little Ice Age, a period when temperatures across Europe were significantly lower than normal.
So the trees grew more evenly throughout the year, making the density differential relatively small.
Student: But you said someone replicated the Cremonese wood.
Professor: The density differential was replicated.
Student: What did they do? Try to simulate an Ice Age climate in their greenhouse and grow some trees in there?
Professor: No, what happened was a material scientist figured out a way to process wood to make it acoustically similar to the Cremonese wood.
He basically exposed the wood to a species of fungus, uh, a mushroom.
In the forest, fungi are decomposers. They break down dead wood.
But this particular fungus nibbles away only at certain layers in the wood, leaving other layers alone.
As a result, the density differential of the fungi-treated wood approach that of the Cremonese wood.