I did a search on "artificial ears" "technical review" and impedance and did not find that this article had been introduced to the community. If I missed it forgive me.
I am finding this interesting, especially after checking out many of the earphone measurements around the web wondering why certain kinks in the charts keep showing up near the same frequencies so often. There are certain resonances in the ear canal that keep causing these kicks apparently.
Here is the link to it for reference which is a 40 page technical paper developed by B&K, the makers of artificial ears for testing instruments.: