Why trust the measurements
Because the method is written down and you can check it. Every headphone is seated deliberately, for the best fit — adjusted for seal and for sound, the way you adjust a headphone before you settle in to listen — not dropped on at random. Most published measurements average a handful of careless placements together. We think that answers the wrong question: you don't listen at a random seating, you listen at the one you fiddled your way to. So we measure the good one, then prove we can find it again.
What gets published is one real seating, never a blend of several, chosen by a stated rule. Both channels are measured and kept. The rig, the seating procedure, and the repeatability numbers go on the page next to the curve, including the parts that aren't flattering — where the fixture stops being trustworthy, and how far the line moves if you seat it again. A measurement you can't audit is just a picture of a line.
Background, for what it's worth: I was employee #1 at Grace Design, where one of my jobs was building the automated measurement system the gear was tested against, and I later ran HeadRoom as president and CEO. It's why I care about this, and it's how I learned what a bad measurement looks like. It isn't the reason to trust the graph — the method above is.
The Art and Science of Headphone Design
I wrote The Art and Science of Headphone Design, a bench manual on how headphones actually work, from driver physics to measurement and tuning. The full reference is free and open at makerphones.com. There's also a print and Kindle edition for anyone who wants it on the bench.
Employee #1
Production, testing, repair, prototyping, and the automated measurement system the gear was tested against. Two founders and me, to twenty people and gear in studios worldwide.
VP Ops → President & CEO
Relaunched the entire headphone-amplifier line: every model from concept through prototype into production.
Building in public
An independent line of audio tools and an open headphone field manual. Running the whole product chain myself, in the open, so you can see exactly how I work.