It's raw vs. compensated with Rtings target response curve, which is represented by the dashed orange line on the first two graphs...
RAW FREQUENCY RESPONSE (with left & right channels on separate graphs):
https://www.rtings.com/headphones/1-4/graph#290/4011
https://www.rtings.com/headphones/1-4/graph#290/4012
COMPENSATED FREQUENCY RESPONSE (with left & right on same graph):
https://www.rtings.com/headphones/1-4/graph#290/3992
Use the selectors above the graphs to choose other headphones and the type of data you want.
It would be nice if there was an easy way to give a simple +/- ... dBs spec over a certain frequency range for headphones, like with loudspeakers. But because of the way measurements are currently done with headphones, it's a bit more complicated than that. There are numerous sites that provide frequency response data for headphones. But unfortunately still not much uniformity between all of them. About the closest we've come to something like that so far is Jaakko's AutoEQ database. But there are potential problems with that as well.
The +/- specs on speakers aren't that accurate either, since it's all done by the manufacturers. And generally tells you very little about the sound in a room. You need something like Harman's spinorama measurements, which provide off-axis and sound power info as well as direct/anechoic info to really get a more complete picture of a loudspeaker's accuracy and performance...
We might eventually get closer to something like that for headphones with the new 5128 measurement system that Jude has been experimenting with. But we're still pretty far away right now. So you still have to do alot of homework to learn what to look for on a FR graph, both raw and compensated. And how to use them to more effectively compare the sound signatures of different headphones.
There isn't universal support for this among the
users of headphones either. Let alone the vendors. So there is that to contend with as well. So some of us are more interested in this kind of thing than others.
