I am trying to find a mathematical model of a loudspeaker in an enclosure. By this, I mean an equation that describes the electrical impedance of the speaker as a function of the physical characteristics of the cone and the air in its enclosure.
As an analogy, I am familiar with the model of a servo motor, which relates its electrical impedance to the inertia of the load and the shaft speed. You can read an article I wrote about that at https://www.researchgate.net/publication/355587208_Regenerative_Brake_Charges_Your_Caving_Lamp_Whilst_You_Abseil.
Interestingly, one of the terms in that expression is the inertia divided by the product of torque constant and voltage constant, which has the dimensions of capacitance, showing that a electrical model of a servo motor includes a large capacitance. I am looking for something similar for loudspeakers, which shows how the physical characteristics of the enclosure and speaker are reflected in its electrical circuit model.