Driver breakin period, what’s the science?

So have these new speakers and been told they need a hundred hours to be broken in, and then sound will improve.

What’s going on as break in occurs?  More important for tweet, mid or bass?  
My initial listening has simple vocals/music passages sounding very good, and more complex and very layered sections that may have potential to improve.  
How does one tell for sure if the speaker's sound is really changing over time, and it's not due to things like variations in hearing over time, air temperature or pressure, mood, acclimatization to the new sound, etc.?

A bench test can be performed with the driver playing a sine wave frequency at or near speaker free-air resonance (fs). Keep driving the speaker for a known period of time. Measure the fs at various periods of time. If fs changes due to speaker suspension break-in or loosening up, the fs should decrease. Manufacturers should already know whether break-in is needed.
How does one tell if anything is really changing over time? If you rely on some kind of test that is dishonest. Why? Because then the question is how can you rely on the test? How can you be sure something there hasn't changed as well? But really, bottom line, who is it that is doing all this relying, anyway? There is no escape here: it is YOU! 

Learn to listen. If you can't hear it, what do you care that others can? If you can hear it, what do you care that others can't?

I don't really care that some people can't hear. My only concern is putting the fact out there that it is possible. How far they go with this knowledge is their business. Just wish people wouldn't confuse their inability with mine, or anyone else's. 

I know, don't hold my breath....
^^ we wish you would... permanently