Understanding loudspeaker impedance
The resistance and inductance of the loudspeaker coil is part of the impedance. However, a loudspeaker is a motor, which couples the electrical input current to a mechanical output force, and a generator, which couples the mechanical velocity back to voltage again. This means the mechanical parameters of the loudspeaker are also important parts of its electrical impedance.

Mechanically, the loudspeaker coil and cone have mass, and are supported by at least one spring, the cone suspension, and often another spring in the case of a closed box, which is the compliance of the air in the box. This mass/spring pair has a resonance, usually down in the high 10s or low 100s of Hz. In a ported box, the mass of the air in the port forms another order to the resonant system, this is usually done to push the resonant frequency down. 

The air has an impedance (it is medium through which waves propagate), though the cone is usually poorly coupled to this, especially at low frequencies, which is why speakers tend to be so inefficient.

There will be some capacitance across the loudspeaker coil. I suspect the electrical resonance with the speaker inductance is well above audio, and well damped by the resistance.

So it's a bit more than just the inductance and resistance.