Hi Rick
"“thinking we are talking about different things” Denney
Well maybe yes maybe no, likely more a different vantage point.
In fact, we can measure just about any physical property one can think of, what one cannot do well is tie a feature in a given measurement to "what it would sound like".
Granted, if one has measured many many loudspeakers there are things one can guess in a set of measurements would correlate to what you hear but many things are not visible in a measurement.
A key issue is we hear in 3d while technically speaking, just two reference points can only capture one axis accurately so our hearing encompasses a great deal that isn't obvious. My post with a link to Doug's LEDR recordings and the work behind it are a sample.
Don't get me wrong either, i am not saying measurements are not important, they are critical to invention of anything new or improving anything old, rather that the connection to what we "see" in a measurement vs hear from it is often more tenuous than some might think and in some cases baffling. Baffling because ones ear brain combo seeks information and without our awareness, discards noise and interference. Often you can't hear flaws clearly but if you defeat the stereo hearing process one can often reveal new things.
If you have a good set of headphones and a good measurement mic, a fun test is to to listen to the microphone in mono with headphones. Best is to wear them for a few min, set the level to sound "normal" listening to household sounds and better yet others talking.
First you will notice all the room sound, your ears have directivity and noise rejection but the mic and headphones defeat that process.
Then, when your comfy, play some of your favorite music through ONE loudspeaker.
If you play pink noise and move the mic around near the speaker, you will easily hear the radiation pattern it produces and often one can find lobes and nulls via headphones.
Most people will hear a dramatic difference, where voices in the room sound pretty normal speakers often sound very different and not in a good way. I would caution that often, once you have heard a flaw in a loudspeaker exaggerated via gen loss recording, it will probably be audible once you go back to normal listening. As a speaker designer, this doesn't tell you what to fix and there is no "number" but it can be a strong arrow pointing to where you need to look.
If you make a generation loss recording in an anechoic condition, you hear an increasing caricature of what's wrong and like electronics and recording tape, the more generations one can pass with acceptable quality, the more faithful the process. You would be shocked or a least surprised to hear how few generations most loudspeaker can go and still be listenable.
By far, loudspeakers are the least faithful to the signal of the entire chain, on the other hand if you can pass a number of generations, that doesn't hurt when when captured on a cell phone or camcorder.
If you have headphones, here are a couple recordings I made, testing a new speaker at my shop and at a couple old sound checks.
https://www.dropbox.com/s/g61e95t8eve7gux/20160623090318.mts?dl=0
https://www.dropbox.com/s/va4mihvefqyxk24/20130723140018.mts?dl=0
https://www.dropbox.com/s/tnsw5mb4v5vdlwq/20120726122124.mts?dl=0
Best Regards
Tom Danley
Danley Sound Labs