In the present study, the sound transmission loss through the air-filled rectangular double-walled sandwich smart magneto-electro-elastic (MEE) plates with porous functionally graded material (PFGM) core layer under initial external electric and magnetic potentials, and external mean airflow is studied using the third-order shear deformation theory (TSDT). Three states of uneven porosity distributions are considered for PFGM core layer which are supposed to vary along the in-plane and thickness directions based on the power-law model. The derivation of vibroacoustic equations in the form of coupled relations is realized by implementing Hamilton’s principle. An analytical approach, i.e. second velocity potential, is exploited to solve them in conjunction with double Fourier series, and the final result is the desired sound transmission loss (STL) equation. The developed solution is investigated in terms of its accuracy and precision via a comparison with other available data in existing research. Parameter studies reveal the impacts of the initial electric and magnetic potentials, porosity distributions, incident angles, acoustic cavity depth on STL through the double-walled sandwich smart MEE plates.