Nate, you are welcome!
Sound holes and air flow - interesting article
Fascinating! I have always wondered how much the shape of the sound hole matters since i tend to build very simple dulcimers that usually just have round holes. They're pretty loud so I didnt think it would matter but now i have one more angle to come at my next build from!
An excerpt from the MIT study the article is discussing:
"By determining the acoustic conductance of arbitrarily shaped sound holes, it is found that air flow at the perimeter rather than the broader sound-hole area dominates acoustic conductance"
and a quick summary I thought was poignant:
"the circle is the shape with the lowest conductance"
Basically from my understanding of the study, any long narrow shape is ideal, not necessarily an f hole, although they are aesthetically pleasing. The is very fascinating since pretty much 99% of guitars use round soundholes! It also makes me think about placement more. Since the edges of a soundboard are the least resonant parts, maybe having a long narrow soundhole that runs at the same curvature as the edge of the soundboard just an inch or two in from the edge would allow you to get the most efficient shape with the most efficient location? Definitely a bit above my comprehension level for now, but I will be elongating my soundholes on my next build.
Thanks for sharing!
MIT Study: https://royalsocietypublishing.org/doi/full/10.1098/rspa.2014.0905#RSPA20140905C3
Saw this article from 2015 referenced earlier on Facebook and found it interesting. I am not a luthier but possibly could apply to dulcimer also. If this article has already been referenced on this site, I apologize in advance.