I used to think a speaker cone moves like the waveform of the voltage being applied to the coil, ie high positive or negative voltage = speaker cone position is inwards or outwards.

I realised this is wrong... the voltage applied to the coil is proportional to the force being applied to the speaker cone, not the cone's position. The cone moves like the derivative function of the voltage waveform applied to the coil, ie high positive or negative voltage = high positive or negative movement of speaker cone.

Then I realised this is wrong too. The voltage applied to the coil is proportional to the force being applied to the speaker cone, which is proportional to the acceleration of the speaker cone by F=ma. The cone moves in the double derivative function of the voltage waveform applied to the coil, ie high positive or negative voltage = high positive or negative acceleration of speaker cone.

Then I realised this won't happen... the effect of air resistance on a speaker cone will be significant, probably more significant than the inertia of the cone.