What happens to a reed during the break-in process?

Hey friends,

I was wondering if any of the more techy people on here had any idea of what physically is happening to a reed during the break-in process.

Even when a reed is the right strength for me out of the box, I'll notice that new reeds tend to have a darker, less focused sound with a more dull articulation. I don't think it's as simple as them being a little hard. Usually after some time (Could be a few days, could be a week) I feel like they get used to vibrating and all of a sudden pick up more overtones in the sound and articulate much more cleanly. Does this have something to do with the pores on the reed closing?

Not that I anticipate this knowledge making much of a difference in my process, but often I am unsure when to start sanding a duller sounding reed or when to simply keep playing it in hopes that it'll break in. I'll notice that to the touch newer reeds definitely feel stiffer and less pliable.

Thanks for any insight you can provide!