Speaker Cabinet design: Interpreting Thiele-Small data, using sofware, and tuning

[Malcolm Irving]

If you have a speaker in free air and give the magnet a thump you can hear the resonance of the cone. Now short the speaker terminals together and do it again, you can hear that the resonance is now damped.
Now imagine two speakers in parallel and give each a simultaneous and identical thump – you are back to the undamped case. This is because the back e.m.f. produced by each speaker is identical and no damping current can flow. (It is like connecting two identical batteries together pos. to pos. and neg. to neg. – no current flows.)

[SoulFetish]

okay, so I'm realizing that I have some blind spots in my knowledge of resonance and damping. I want a better fundamental understanding of the role they play in AC circuit relationships. What are some good resources.... basically I'm all ears to any info you got.