JJ’s post should be a sticky. Yes, it is easy to oversimplify. I think when it comes to defining the final target for studio calibration we have not reached the point where the same target frequency response, measured in exactly the same way, sounds the same in different rooms with different loudspeakers! JJ alluded to the issue with loudspeaker horizontal polar pattern and its interaction with wall reflections as one cause for the variation. Other variables are loudspeaker distance from the listener, room size. Room “reverberation” curve.
With all these variables, it’s absolutely necessary to combine subjective judgment with the measurements. The measurements to help provide consistency and a baseline to compare. The subjective judgment to help deal with, largely, bass response below about 125 Hz and treble response above about 5 kHz. I find that the smaller the room and the nearer the loudspeakers, that I have to bias the bass response upward to get the same subjective perception as in a larger room. I have an empirical method to arrive at treble response and it works very well for me. I measure using the same measurement method as I always use, and then I know that some kind of HF rolloff will be required. But how much rolloff? It differs, and I have a method to help ensure consistency within that slippery subjective context. I don’t have the time to tell you about that today!