Let:

• e(t): Electrical Potential (voltage) applied to copper electrons

• M_{\text{coil}}: Mass Structure of voice coil

• M_{\text{cone}}​: Mass Structure of diaphragm

• I_{\text{air}}(r, t): pressure (Particulate Motion) in air

• E(t): total energy of the system at time t

Then:

\begin{multline}
E(t) = \int_{\text{copper}} G_e(t) \cdot R_e(t) \cdot \delta\left( G_e(t) - R_e(t) \right) \, dx \\
+ \int_{\text{cone}} G_c(t) \cdot R_c(t) \cdot \delta\left( G_c(t) - R_c(t) \right) \, dx \\
+ \int_{\text{air}} G_a(t) \cdot R_a(t) \cdot \delta\left( G_a(t) - R_a(t) \right) \, dx
\end{multline}