As HTL's graphs have some unusual features, and because the measurements that generate them may be unfamiliar, I'm preparing a series of screencast videos to help with navigating the test results and understanding them. When further videos are added, I'll flag this up on the Latest page. They are best viewed full-screen.
Headphone Test Lab's graphs incorporate a number of unusual features which aid their interpretation and clarity. This screencast video describes and demonstrates them. (Duration: 7m 13s.)