Nice article. I wonder if the Helmholtz motion does anything to explain why a violin can seem to sound lower in pitch than the fundamental pitch of the string. I do not know if this is a right perception or not, but when playing a violin against a mandolin tuned the same, the violin seems lower. (I play mainly with fiddlers, who get a good growling sound - it may be less true for classical players.) Yes I know about the mix of harmonics on the plucked instrument, but it seems to hold even if one plucks in the middle to try to pick out the fundamental. And I think that it is true also if one compares a plucked violin to a bowed one.
Does the Helmholtz motion happen at a lower frequency than the fundamental?