The initial derivation of SEA arose from independent calculations made in 1959 by Richard Lyon[1] and Preston Smith[2] as part of work concerned with the development of methods for analyzing the response of large complex aerospace structures subjected to spatially distributed random loading.
[3][4] While the modal approach provides physical insights into the mechanisms that govern energy flow it involves assumptions that have been the subject of considerable debate over many decades.
Each component can support a number of different propagating wavetypes (for example, the bending, longitudinal and shear wavefields in a thin isotropic plate).
The SEA equations contain a relatively small number of degrees of freedom and so can be easily inverted to find the reverberant energy in each subsystem due to a given set of external input powers.
Typical applications include: Additional examples can be found in the proceedings of conferences such as INTERNOISE, NOISECON, EURONOISE, ICSV, NOVEM, SAE N&V.