Stupid speaker test question...please help a n00b


Why aren't speakers tested by measuring the output sound waves vs the input wave signals? Would this not be the easiest way of testing distortion introduced by the speaker? Assuming you control all the other parameters of the test of course...

Thanks for the help!
spartanmorning
Ears are less sensitive to distortion at lower frequencies. 5%? 10% I know it would look awful on a chart.
At higher frequencies ears are much better.

As for sensitivity being the sole measure needed? Well, I'd like to know if I were getting a speaker with high phase angles before popping for that good tube amp.
The dyns and va should be compared in optimum setups in the same room.
It is easy to have that much variation so that the speaker with better bass spec actually sounds thinner. Maybe the speaker is built to a higher 'Q' or there is an amp issue with speaker / amp not getting along at low frequencies where a high phase angle may play havoc with an amps ability to produce enough power. All sorts of other possibliities exist.

Now, I dont' know....how easy IS it to measure speaker distorion and how many flavors does it come in? Is time / phase coherence part of distortion?
Doing such measurements sounds like a legitmate use of an anachoic chamber and mega bucks worth of amp.
We are well beyond my knowledge level (obviously) but I have to say I find this field of 'hi-fi' quite frustrating. There seems to be so much misinformation and disinformation that obtaining any semblance of understanding would require a formal acoustics degree of some variety.
"I have to say I find this field of 'hi-fi' quite frustrating"

You're not alone. We are here to learn.
IMHO, John Dunlavy built some of the finest loudspeakers, and he depended on tests more than most. He seemed to think that step and pulse response were particularly important.
Square wave reproduction (as noted by Unsound) is a darned good objective test. Decades ago Ohm cited this in their promotional material. I have been told that a few other speakers pass this test.